you go first (you go ahead)

Hello~ Can you help me say this naturally please?

Situation 1.
A and B are on the way to go to school.
A ran into his friend and say to B.
A: Hey, sorry, you go first (you go ahead), I have something to talk with him.
B: Oh, ok, see you class room then.


Situation 2.
A and B decided to tell their secret to each other.
But no one wants to start first.
A: You go first. (You go ahead).
B: No, you go first. (You go ahead).

They're natural enough to me.