With respect to Best Buy, I would take any timeframe they give you with less than a grain of salt. They first promised the Mavic on Oct 30, then Nov. 30, now it's still 'coming soon.' It's true that they were getting jacked around by DJI like everyone else, but their communications were terrible... everyone you would talk to at BB would swear up until the day of shipping that everything was on schedule, then two days later you'd get a 'Sorry Charlie, we don't really have it' email, and I'd expect the same performance with the P4P. I would advise buying DJI products from one of the smaller dedicated drone vendors, most of which have much better communications.
I got mine from B&H, I was told their extended return policy applies to the P4P as well so I have until February 1st to return it if I decide against it or need a replacement due to any unforeseen defects etc. I was told you just have to keep everything that came with it including stickers over the sensors and on the arms and they will accept the return with no stocking fee and no questions asked.