Do they act approachable? people usually give hints if theyre open to chatting. If they wear earbuds or something it usually means they want to be left alone for example. If there arent any red flags like that to tell you not to bother them just start simple and see how they react. Say good morning as you walk by, smile and wave, but don’t try to start a full blown convo. See how they react. Do they seem startled, uncomfortable, or nervous? Probably leave them alone. Do they smile back and return the greeting happily? Thats a good sign. Maybe next time you see them say something like, “Hey! Seems like were always here at the same time. You work nights too?” If at any point they give signs like, short non-commital answers, looking around and not at you, being annoyed nervous etc, they dont wanna talk and you should say bye and go do your own thing.