OOoh a new house - how exciting!
It can be a very stressful time for cats though, so you do right thinking in advance of how you can help the process. I know having done it with one cat, that was pretty stressful for us all !
I would say before the removal men arrive, ensure the cats are enclosed in one safe and secure room. Try and empty it of anything other than essentials. Put the cats things in there - beds, food, water, litter trays. Make sure there's a note firmly affixed to the door asking people NOT to open the door. My tip would be to empty this room last, and either take the bedding, toys, food etc in the car with you, or put it on the van last - that way you can get it out first, and reverse the process at the new house - first things to go in are the cats' things in their designated safe space, and then the cats, making sure the door is securely closed and again marked "Do not open."
Put Bebe and Bruno in their cat carriers just before you're ready to go. Make sure they're secure. Load up, and off you go.
I would suggest Pet remedy plug ins - one upstairs, one downstairs. Dont let the cats out of their safe room until all of the removal men have gone and you've got things largely where you want them - even if its just putting the boxes in the designated rooms - the familiar smells will reassure them about the unfamiliar ones, all being well. Make sure all doors, windows and exit routes are shut and secure before letting Bebe and Bruno out. Because the house will be new to you as well as them, I can't emphasise this enough - visualise anywhere there may be an opportunity for escape, and make sure it isn't an option before you let them out to explore.
We had a cat who decided to clamber up our open chimney once.......
It took weeks to get the soot out of his fur.
When you do let them explore, try not to feel anxious about it - they'll pick up on that. We went round showing Paddy all of the "new stuff" and just chatting to him about all the advantages the new house had (he was relaxed after the first couple of hours). As Paddy was an indoors/outdoors cat, we'd planned to keep him in for two weeks but he was frantic to get out after a week. Yours may find the great outdoors at your new house a fascinating prospect, so just be vigilant.
If you can, try to recreate your cats' routine from the old house, so that they know although the property may have changed, the daily rituals go on unchanged - that's very reassuring for them. Try and play with them as often as you can so things go on unchanged.
And on moving day, make sure that once the cats have been settled in, and your front door shut for the night, you have a nice bottle of wine and something tasty to eat, because you'll be feeling frazzled, and ready for your bed.
We took Paddy up to bed with us that first night, and again, that maintained his routine and helped him to feel "safe". Tess also snoozed in the bedroom with us
(Lord, I miss that dog; she was the sweetest!)