Transferring My Internet Tomorrow...

Hello. I'm moving to my new apartment tomorrow. I'm trying to change the plan location. I am using all my old hardware. The previous tenant had Xfinity, so no installation should be needed. But the moving thing on the Xfinity site insists I must set the date at least 5 days before the transfer can go through. But I don't see why that would be needed, if all I need to do is hook up my stuff. If someone could help me set this up so I can have my internet transferred tomorrow, I'd appreciate it.