Can I use just with present continuous as in:
Mother: We are running late for dinner, where are you right now? Son: I am just getting home.
Friend A: Did you finish the last answer? Friend B: I was just finishing but the examiner snatched my copy.
Father: Have you finished your homework? Son: No, dad, I am just starting it, I need one more hour.
Are these uses of just grammartical and idiomatic?
I am a non native learner.