Question about transitioning from old phones to new phones.

We will be using our own non-provisioned phones, the Poly Rove40’s.  Our main number will be ported over to Ring Central on Tuesday (1/27) at 10 am CST.  This is in the middle of our busy time.  Can I provision the phones ahead of time (a day or two ahead of time) to where I can just unplug our old phones and plug in our new phones once we get confirmation of a successful port, and not miss any calls?