Welcome to AGL Community!
This is not a problem at all, people often need a cross over between houses, great thing is that you can have connections for as many properties as you would like for as long as you would like.
All you need to do is figure out what date you need the power on at the new house, and work out the absolute last day you will need power at the old house, remembering final cleaning as well, then let us know to disconnect it the day after.
You can book your move online here, and stipulate the different dates without an issue.
Good luck with your move!