There isn't a set date yet, but it's planned to be the day after the takeover offer closes.
And the AYS is scheduled to delist from ASX at COB on 31 March, so it's possible that if you don't sell on market or accept the offer before 30 March you will have to wait for all the distributions, because there won't be a way to dispose of you shares.
From the Target Statement, page 1Close of Offer Period (unless extended or withdrawn) 7.00pm (Sydney time) on 30 March 2021
Major Distribution Record Date Expected to be 31 March 2021
Rod