Last Payment to Contractors- what % of job cost and when?

[Jonathan C.]

Hey guys--

what is your rule of thumb for general contractors with how much of the total job cost you pay them at the end (in terms of a % of overall job cost), and when do you pay it? i.e. after final punch list, after you've had all inspections from permits you've pulled, after the property is under contract and buyers home inspector inspects it (I assume that's too long to wait), or some other way

I am having contractors looking for payment before I am comfortable paying, so I want to know what recommended practice in this area is.

thanks for any help