Apple sent out invites yesterday for a pre-Halloween Mac announcement. The MacBook Pro is believed most likely to get updated at the event, but honestly iMac is likely not out of the question or maybe even MacBook Air. So to avoid buyer’s remorse, maybe wait until after October 30th to buy a new machine.
If your return period has lapsed they won’t refund you but they will probably allow you to exchange it against an equivalent M3 machine. Talk to a specialist in store and they can ask a manager. Can’t guarantee this’ll work but so long as it’s an exchange as opposed to a refund they may well make an exception. That’s assuming we even get an update to the MBP line. I think the iMac is a much more likely candidate for an M3 update but who knows.