Question on sending in my product with UPC Code vs FNSKU

I have started selling my product in retail stores, and got my latest inventory printed with UPC instead of the FNSKU. Through some searching on this subreddit I decided to send in a box to test (16 units).

It says they are checked in, but not “closed”. How will I know when they have accepted the UPC Code? is checked in good enough?

And if they do not accept it, can I just pay them to stick on the FNSKU? I have about 2,000 units sitting in my garage to send in for the holidays, and I’m stuck on whether I can send them in or not.