There are actually 2 types of payments for affiliates. The first is instant, the other is delayed.
For instant commission payments, the payments will be sent to your account instantly, at the time of purchase. This is paid to you directly from the vendor's Paypal account into your own affiliate Paypal account.
Delayed commissions means that the seller has up to 90 days to release your commissions for you. They will release your funds directly from their account into your own Paypal account sometime within that 90 days. The 90-day limit is to allow for refunds.
You can, of course, always contact the vendor to see if they would be willing to release your funds early for you, or to change you from delayed to instant (or vice versa). That decision would be completely between the vendor and the affiliate.