With Timeless, I allow a matte canvas to outgas for about 24 hours. If you take it straight from the printer to coating, you can get very faint bubbles, not the ones people get from too much timeless being sprayed, but tiny ones, more around the weave lines. They will show up more on solids, especially blacks, dark blues etc. This issue seems to go away after the 1st 24 hours or so.
After coating, I will let the canvas sit about 1 hour then take it to stretch. You don't have to wait as long as with Glamour II. Timeless will be dry in most climates within 15 to 20 minutes. However with Lyve and timeless, you can wait as long as you want. Print and coat, then store them rolled up.
Leaving a matte canvas uncoated is fine, however, it's so easy to scratch it, or get other impurities on the face that I tend to try and get them coated as soon as possible.