I would try not to give the shots all at the same time if possible. It's really hard on their little systems. I think the health certificate is only good for one month so make sure you don't get it too early.
The only other things I can think of is how well do your cats travel generally? If they tend to be very stressed you may want to talk to the vet about getting some acepromazine (a sedative). Are you flying or driving? If flying have you cleared everything with the airline? Like types of carriers required, cabbin or cargo, and extra cost. If you're driving and they aren't used to it, you may want to take them on several short car trips first.
Good luck on the move!