I agree with Jen and Naomi, close off some rooms so the cats have a smaller space to adjust to. Once they're settled in, they'll have a great time exploring the new rooms

If you can, I'd think about boarding them for a couple of days while you unpack, set up furniture etc. All the uncertainty and noise can be very unsettling for cats. It might be stressful for them at a cattery, but I think it's much less stress than sitting in an empty house that's being unpacked.

When you first bring them to the new house, make it a time when you have a few hours free so you can sit peacefully near their things and help calm and pet them. It seems to help them settle more quickly.

Good luck!

Jen, don't cats love stairs!!! Mini and Jasmine used to have a daily happy hour racing up the down the stairs in the old place. This house has no stairs boohoo, but it's bigger so they have a longer distance race now