When we built the Teurlings Stadium they were installing plumbing fixtures the Wednesday before the Friday night game. All the subs had some people on site the night of the opening game. Good thing too, because there were some plumbing problems. The fire marshal did some pre inspections and we were all good to go on Friday night.
I think they will be fine. Installing the seats should take no more than two weeks. The restrooms and concessions will be tight though. The bell tower is not a life safety item and can happen any time. If it's prefabricated then no problem. Lets see what it looks like in a month. I think you will be surprised.
Just because there aren't plenty of people working doesn't mean lack of progress. If you have too many trades trying to work in the same place they just get in each others way.