I note the comments about unproven travel plans for The Amex necessitating a Sat 3pm kick off for the first league match. However IMHO the whole point of the ramp up games, with incrementally larger crowds allowed for each and hopefully culminating in a capacity attendance at the last is to prove the travel and contingency plans work effectively so The Amex gains its safety certificate - well ahead of the league season.
Assuming this goes ok there should be no reason for the first league game to be nailed to the Sat PM, although of course this will suit most. But as suggested earlier the possibility of live TV coverage may determine otherwise.
I suppose if the safety certificate has not been signed off ahead of the first league game then there could be a restriction on the use of the stadium and possibly the timing of the first league game(s) - but cannot see that happening unless there is a monumental cock-up. However this would seem to be a worse case scenario and highly unlikely given the pre-planning that one assumes/hopes is already taking place/being finalised?
Everything else at The Amex looks to be under control and presume that someone will not forget something obvious i.e. to order a few dozen FA spec footballs?