then you are working for the wrong builders. talk to their other subs, look at other work they have done, then give them a price.
I would be surprised if you could get deposits from builders but, you should be able to get paid within 2 weeks of completion.
On a prime contract the amount you can get down is a function of the size of the contract. If it's a patio, sidewalk, or driveway, maybe 50% down, balance upon completion (when you strip the forms). If you work it right you might be able to get the other 50% while your guys are cleaning up after finishing the mud.
If the project involved multiple parts (footing, stem or foundation wall, and slabs) you can probably break the payouts into separate projects/payments.
On a whole house, I would make two payments. One for the Footing/Stemwall/Slab (including excavation, grading, and steel) and the second upon completion of patio, drive, sidewalks.
If you're going to be a contractor your most important tool is working capital.
no one ever wants to pay and mostly seems to be home builders... and its sooo annoying as we work to make a living.