Hi. I'm a bit late to this conversation and wanted to take it a bit of a different way instead of arguing about whose 50mm lens is the best and so forth
First off, let's talk a bit about what being a "pro" is. A pro does NOT necessarily take better images than anyone else. Instead, a pro, at least one by my definition, always delivers professional quality images, no matter what the situation, and does so time after time after time without fail.
Let's take a look at the last part of that sentence: "always delivers professional quality images, no matter what the situation". This snippet holds the answers to some gear decisions. As a pro, you have to get the shot, and the shot has to be at a certain level of quality. It doesn't have to be the best technical shot with the best MTF graph resolution, but it does have to be sharp enough. The important part of that snippet is the front part - "always delivers", and the last part, "no matter what the situation". That means a pro has to be a shooter who knows his gear inside and out and sidewise, plus the gear itself has to perform in any situation under any stress and not get in the way of the "always deliver" part, and the pro has to be a problem solver when things go sour on a gig, as they often do.
Right there, in my mind, unless you are working in a scenario where the absolute ultimate in image quality is needed - say, a landscape artist who sells big prints and has to compete with medium format and large format film guys - the most important thing is that the gear never gets in the way of you getting the shot on a consistent time in, time out basis. And here is why I don't advocate running to the Tamron lenses or even the 24-120 Nikon, and even perhaps the Sigma, even though the Sigma glass is bloody excellent. (This is NOT to say that third party glass isn't good - it certainly is. I own Nikon, Sigma and Zeiss, but my needs are different than yours as I shoot static subjects with high quality as an objective; I don't shoot birds or athletes)
Getting the shot means the lens/body combination has to have the synergy to get the highest hit rate in terms of AF, particularly if you'll be shooting things that move as opposed to things that are static. Given what you've told us, my thoughts are that the consistency and reliability of "getting the shot" has to take precedence above all else.
So skip the third party AF glass for now. As you evolve as a pro, and need a lens for image quality reasons alone (say, you need something special because you're suddenly asked to do some studio portraits), then you can look into things like the Sigma 35 and 50 arts, the Zeiss manual focus glass, and so forth. I know the suggestion of skipping the third party glass is going to anger some people, and to make sure I'm being clear - there are excellent third party lenses. In static use cases (studio or landscape), they at times are even better, although incrementally so, than the manufacturers equivalent. But with things that move, where AF is involved, it's about getting the shot, and that category is different than having the best ultimate image quality potential. And let's think about this: If you're shooting, say, an event or race, the odds are that most of your competition will be shooting their Nikon/Canon 70-200/2.8's. If you show up with your Tamron or your F/4 lens, well, it will "do", but over time, over the long haul, on a consistent basis, my money is going to be on the other guys getting the shot more than you. You don't see McNally shooting with a Tamron or Sigma zoom when he's on a deadline. I know several high end pros including one world famous corporate shooter who is extensively published, several NFL (American Football) shooters, a high end music industry photograper, and a few guys making their living doing weddings and a few doing theater and dance. None of them - zero - shoot anything but manufacturer glass at their core focal lengths with the zooms. And most of these guys pay for their own gear. So you have to ask yourself why that is and if it's really worth going cheap and skimping on a lens that none of the serious pros would ever consider skimping on. Again - if you had told me you are shooting landscape to be printed 30x40" on a regular basis or that you shot fashion in NYC, I would not be telling you to avoid third party glass - so I'm basing this recommendation on what you've indicated you will be doing.
This also means my suggested starter pro kit is going to blow your budget a bit, but I also believe you should try, as best as possible, to buy gear once, even if it means a bit less of it, as opposed to having to buy twice because you went second rate the first time.
I don't shoot what you do, but I imagine you'll want to do a lot of close ultra wide stuff like I've seen Joe McNally do, and the best lens for that is easily and obviously the 14-24 Nikkor. It's best at the wide end of it's range (where it is better than the 16-35 for sure) and still quite good at 24mm. The 16-35 is strong in the middle, but nothing special at 16 and certainly weakest at 35mm. So if wide angle is in your mind, the 14-24 is the must.
No pro I know goes without the other two - the 24-70/2.8 and the 70-200/2.8 - these are key, core focal lengths, and in Nikons case they are both excellent. The 24-70 is best from 28-70mm and the 70-200 is good pretty much anywhere, and is particularly excellent in the middle focal lengths in the moderate subject distances. I would take the 70-200 over the 105/2.8G VR Micro at 105mm for general purpose work each and every day.
So yes, that blows the budget, but it's the base kit. The next question is that if you have to "cut" something for the short term, you have to take a look at the subject matter and focal lengths you need the most. If you think you can live without a wide for now, then you get the other two. If you feel you won't live between 28 and 70mm much, then you perhaps get the cheap 50/1.8G Nikkor (skip the 50/1.4G honestly) to hold you over as it's only a couple hundred bucks. I'm betting the 70-200 will be a core, key lens and as we've discussed, this is somewhere I would NOT want to skimp.
Everything else you look at down the road once you've earned some cash and have a better idea of what you're going to do and what focal lengths you really need to deliver the goods reliably, day in and day out.
Now, once you've got a core kit of lenses, you need a second body even though initially you can use your fathers as a backup, and I absolutely second the other poster who talked about lighting. Lighting makes a huge difference if you plan to get serious. While I am beyond lucky to have a very nice lens collection of the best from Zeiss, Sigma and Nikon in the focal lengths I primarily shoot, I am not a venture capitalist with an unlimited budget either, and recently I have been allocating most of the available equipment funds towards lighting and modifiers. At some point you need to think out your strategy and choice of a professional strobe system as well if you find you need such a thing. That won't be cheap either, but light makes the shot and investments in better lighting generally pay far greater dividends than having the coolest or latest gear-of-the-month.
Good luck with your decisions and I wish you well.
-mike
