On commercial work, allot will depend on how the job is financed, on some larger jobs the GC will usually wait for the bank to approve either a construction loan, or a secured note, with payouts going to the GC as the job progresses, in either case, there is no need for a down payment, the money is secured.
The sub contractors, in most cases do not have this same protection, so payment terms, become an important issue, How these terms are structured will depend on the project size, GC's credit report, years in business, experience, and past performance. If the GC fails on a credit check, has limited experience, and or a new business, you may want a down payment, and a scheduled progress payment plan.
It's not so much about getting money up front, as it is checking to see how the project is financed, and agreeing to terms, that will allow you enough cash flow, to continue operating..