I wouldn't trust the USPS to forward our mail and only our mail ever. We've had children move out of our house and everyone in the family has mail that goes to their new address. What a nightmare. It also changed our CC and Bank addresses even though we don't get any hard copies of CC or Bank statements.
I will do just like I did when we switched to a UPS Store. About 2-3 mos before the change, I will manually change everything with the individual CC or Bank. Most are accessible online, but still takes awhile to change.