LOL I use "hurry up". Because I don't like the word potty (not sure why) and nothing else seemed natural to say whilst stood out in the dark in front of the apartments.
But, what I would teach first (after their name, house-training, getting them used to the kennel/crate and general socialisation) is "sit". That is the command I use most... before eating, putting leash on/off, before opening the front door, before crossing roads...