No clue on how long. But after giving it a few days off I would train whatever you can without grip. Use machine to train your whole body pretty much. If you aren't a member at a gym with machines just get a 7-14 day pass or something and I am sure you can work it out. Hopefully someone can chime in on how long it should take to heal. If it was a toe, I'd just tape the shit and deal....but the thumb is a bit more important.