If you log on to your AADSAS account, on the left hand side you can find a link "ADEA AADSAS extending offers of admission." The link will provide you with the information you want to know. looks like it's april 5th.
I think it's around April 1st, where most places require a second deposit.. To decline nicely.. I think you should write them a letter of withdrawal.. hope that helps 🙂
Boy so many people have multiple deposits in! Hopefully people send them in before April 1st so people who are waiting can be notified sooner rather than later.