I seriously doubt you'll be able to get a full charge in only a half hour. And plus that's a half hour that you won't be getting your notifications on your wrist.
Sounds like Apple's old mantra of "fills 80% in 1 hour, fills 100% in 4 hours" battery charging speak. Aren't you supposed to not do those mini-charges on batteries? I think if something has a non replaceable battery you really want to avoid charging half an hour over dinner.
How long do you predict it will take to fully recharge a ~350 mAh battery?
(For reference, it takes just over two hours to fully recharge an iPhone 6 with it's 1810 mAh battery.)