I have been involved in both residential and commercial buildings. The 10% hold for a year is total BS, unless you are involved in commercial work. And then, it usually applies to major construction (multimillion) or public bids(schools, government work)
The OP has not told us what type of garage construction is being done, is it stick frame or pole building. What is size? Is it bare bone (no interior fit out) or is it a finished garage maj hal?
Dont forget, pole buildings take 2 to ? days, depending on size, not including slab pour. Stick frame takes longer.
In the end, it will be a discussion he and his builder must have and agree upon, usually stipulated in the contract. Most require a certain % down payment. Those can range in the 5% to 15%.
I really like(not really) the mention earlier where it was mentioned a GC should be able to cover all expenses until job completion. HAHAHA You have never worked in the building industry have you? GC's are using money from previous jobs to cover the work being done on current jobs. Subs typically do not wait till the end of the job for payment. Once they are done, they bill it. (Depending on size of contract) Material is typically billed when picked up or delivered. Some suppliers offer discounts if paid in 10 days. SO a contractor that wants to take advantage of that must get the money from somewhere, and thats typically profit from another job.
Like I said above, it comes down to the builder and the OP. I know the OP is looking for a suggestion, but typically, its the GC that determines the pay schedule. The owner can ask for a different schedule or values, but ultimately, it really is up to the GC. I walked away from a few jobs because I was not footing the entire build myself.