Buzzer sounding in the middle of the quarter

[splitveer]

Last night we had the following situation:
Start of the fourth quarter and we inbounds the ball using the alternating possession arrow to the white team. ball is inbounds and the white team runs there offense where they put up a shot (that went in). Right before the shot and while the shooter is in the shooting motion (but hasn't released the ball) the horn sounds. When we go to the table they tell us we have given the ball to the wrong team on the alternating possession to start the quarter.

Here is how we handled it:

We didn't allow the basket and we gave the ball to White based on this is not a correctable error situation. We then made sure the alternating possession arrow was for Team blue.

1. Was this handled correctly?

2. We told the clock keeper to not buzz until a dead ball. Is this good advice or when would be a situaion where they might buzz during a live ball situation?

Thanks!