Here is what I do with my guild. We used to use Preform AV but imo it sucks a large nut!

We get 8 people on vent. Guildies are the best. We have them all spam for AV premade in /2. Once each group is full the 8 people on vent then open up the battle master.

I would then count down from 3 ending on 1 and when I say 1 all 8 of us click on join party. 98% of the time all 8 players get the same AV which means all 40 players get in.

This works great as you ALWAYS get the LEAD! From there is it a matter of spamming info to groups and talking to your group leaders. It's just like the army!

Just make sure you tell the people that are not on vent to not join an AV unless the party leader says too.

Besides from that there is WAY less confusion all around for players and everyone gets in super fast.