I would say the answer must vary quite a bit based on location.
For a 200K - 2M dollar job around here submit by the 25th and usually get paid in 45 days. Don't count on that however - 60 days is not uncommon. Before the job starts you submit a schedule of values for each type of "task". While you do try to front load it, getting 10% to mobilize would not fly in this area. Large buy outs of fixtures or gear are included in your schedule of values and will be billed as part of your regular biling on the 25th. You cannot submit a request for paymnet until they have been recieved. If they are stored off site, additional insurance paper work must be submitted showing that the GC is a payee in the event of loss.
Retainage is also an issue you don't want to overlook. 5% is standard which on 1M is 50K. You won't see that money for 60 days after the project is completed.
While you might think this system is unfair, I really like the system in our area and hope it never changes. If prevents "small" companies from being able to even bid on larger jos because they can't carry money for that long. Luckly that is not a problem for our company. "The rich get richer." Not me, I just an employee.
I do laugh every time I hear someone suggest that YOU should dictate the terms of the contract. Let me know the next time that works on a gov project, or any project with a large GC that knows what they are doing. They will be using the AIA contract and there is no changing that.