I have held contests through my newsletter and there is no need to wait.
The sponsor gives me free accounts to his/her casino(s), in the form of codes.
The winner can go to the casino, enter the code in the banking system and – voila – you have a free account in the prize amount.
I know RTG are equipped to do this – I have done it with RTG casinos.
I assume other softwares accomodate this also.
Besides, we hope the winners will have a good time and become real players, don’t we?