Combining two tanks

Hi All;
I have two tanks and we're moving and I want to combine all the fish into our 90 gal tank with live rock, but I'm not sure when to do it. We're not moving for 3 weeks so my question is should I move the fish into the new tank now, and then everyone gets moved in 3 weeks or just wait and add them together after the move.
Here's the deal.
90 gal has 1 blue tang (and the fish store is taking her back when they move our fish....she's getting too big and is getting all scratched on the rock, plus she's eating my Marine Betta's tail)
1 Clown
1 Marine Betta
1 Skunk Shrimp
Multiple large crabs and snails.
The smaller 20 gal tank has:
1 Royal Gramma
1 Green Chromis
1 Yellow Tail Damsel
1 Skunk Shrimp
crabs & snails.
I'm worried about adding them now and creating a problem with territories where after the move everyone would be finding new spots.
Any advice would be greatly appreciated.

Marinegal

 

I think if I were you I would just stress them once, during the move, instead of twice. Because to them they don't care if they're moving across the livingroom or across town, it's still a move.