Should be done asap and anyone lucky enough should not be excluded from the Celtic game. What should happen is that those not successful should be compensated in some other way but all STHs have paid for all games and it's not fair to just write it off as "well you got his game so now you can't get another game until everyone has had a turn."
Especially since the flag has been taken away from the Livi game.
No one signed up for that. Compensate the people who aren't lucky instead by offering them a cup game free or something as well as RTV access to watch Livi game on TV.
If you're going to exclude folk then ask them to sign up for their preference now. Some people won't want in the livi ballot of there's a small chance they would then miss old firm. Others won't care as they will want the opening game and, all going to plan, would get into Celtic anyway.