From one planner to another: I think I would wait. More cure, better temps, tools or metal may will get dropped by erection crew. Also the finished building will protect from wind, weather and bird poop smile that could cause problems during application and drying. I know some guys that do floors for a living. Their No. 1 tip: proper prep, according to directions for the product you choose.
Just use a nationally known brand that is made for garage floors. I guess epoxy would be best of course. If I was doing it, I would not worry about not finding a part on the floor.
The speckled looks so much nicer and will make the whole garage.