If they are in orbit of a planet, when you start their training they will stay where they are and not follow the planet. (Assuming planet orbital movement is active.)
I personally SM move them back to the planet when they are done training, as I consider it a bug. How can they leave orbit without engines?
Of course, since they are not in orbit anymore, their clock goes up. Though, if you're parking them on the wormhole they'll need a low IFR anyway.