Its a pretty straight forward setup:
Attacker declares ALL combat moves and then you request defender to decide on Scrambles/Intercepts. This indicates you have concluded all your combat moves for the turn.
At this point, the Attacker has passed the point of no return and is stuck with all the decisions just made.
You’ll get a lot of mileage out of requiring the attacker to request scramble decisions with the understanding it indicates they have concluded all their combat moves.
In the case where there are no scrambles, just require the attacker to announce something along the lines of, “That ends my combat move phase.”
Generally it is VERY important when playing in person to make sure you announce the transition of the phases and don’t muddle up combat and non-combat moves. Not saying people all cheat, but it sucks when you lose track of unit movement and end up double moving something that impacts the game dramatically (like moving a bomber to Hawaii in your combat move phase and then non-combat moving it in the same round to one of the smaller islands and now being in striking distance of unprotected Japanese TT which should have been safe but now are not).