"iStock agrees to pay you royalties (the Royalties) within 30 days after the end of each month in which the license or sale was made (except when sales reporting is delayed for transactions that do not occur on the iStock Site, whether made by a Distribution Partner or otherwise, in which case payments will be made in the month following the date such sale is reported) (a Sales Month), by electronic funds transfer (as may be supported by iStock from time to time), or such other method as may be agreed by the parties."
No idea about Payoneer, but for PayPal it's usually taken off our balance by the 5th or 6th, then paid by the 25th; however as you see, they have 30 days, according to the contract.