Bingowings said:

The ideal place would be just as Ackbar says "Move the fleet away from the Death Star" (which would need to be shunted after the fighters have gone in), one of his aides could come back with "but sir it's moving away from us!".

Brief exterior shot of the Death Star drifting out of it's previous orbit.

Then show the screen on the Death Star Command centre targeting the Endor moon and starting the countdown and then continue with the race to the reactor core.

You'd also have to possibly add a line or two of dubbed in dialogue during the command centre targeting saying something like: "we're moving into position for final plan or Order 666(:p)" or something like that. make it sound like the empire planned on having the last laugh after all.