Are COMPO3 Soldiers (USAR) given any time after deployment before they have to report for their monthly battle assembly?

To the best of my knowledge that went away. Guidelines state commanders can grant you 90 days of excused absence since you have all your points from being on AD. But ultimately it comes down to the commanders decision. I just had a group of Soldiers come back from centcom and we are granting them the 90 days, some chose to return after their leave is up and some are choosing to return at a later date.

It used to be 90 days but now it's up to commanders.

I returned in January and it was 90 days if I wanted them.