It is paid in order... the only thing which is influencing it is that nothing gets paid out before 3 confirmations. It might happen sometimes that from two deposits placed in a close time period the last one gets actually confirmed faster. The system takes each deposit in the order they have been made, but the speed of each deposit getting confirmed is out of my hand.

In a previous round I had for example someone who set the transaction fee to zero for example, they were if I remember correctly 3-4 payouts to deposits made after that one, until that deposit got confirmed. But once that happens the system will jump back to it (it always pays out the FIRST UNPAID deposit which has at least 3 CONFIRMATIONS).