Now, obviously players can't be two places at the same time. So if you post that your character is somewhere, then your character is there until you post that you've left. And there is a time difference between moving. If your ship has a warp drive then yes, you arrive wherever you're going pretty much instantly unless its an insane distance away. If you are running on impulse engines you will have to wait a few minutes, say 10-20 depending on distance, before you can say you've arrived (in realtime).

And dont "forget" that you were somewhere else and you magically pop into another planet. Post that you left the other planet and then on the one you want to go to (after allotted time). 