Other possibilities that might (or might not) be worth considering to keep the “fast cut”:
• BB8 reacting first (without TIE sounds), making Rey look up. However I’m not sure it makes sense with the direction Rey is looking in. I think Finn and Rey are on opposite sides of the castle so they wouldn’t be looking at the same thing anyway.
My 2 cents, could you mirror flip the Rey scene so she’s looking the other way?