When should boy/girl siblings stop sharing a room?

I’m currently pregnant with baby #2, and although we don’t know the sex yet, the plan is to have both kids share a room at first so that we don’t lose our guest room (only have three bedrooms, and several out of town friends/family that stay overnight.) Our oldest is a boy and will turn two a couple of weeks after baby’s due date, so they will be almost exactly two years apart. Baby will be in our room for the first 6 months-1 year.

At what age does it become inappropriate for boy/girl siblings to share a room together? My in-laws keep telling us that they (regardless of baby #2’s gender) won’t be able to share for more than a year or so, but on the opposite side my brother and sister shared a room until ages 8 and 9 (which I definitely feel is too old.)

I don’t think it’s too much to plan for ours to share a room until ages 3 and 5 or so. If they are both boys, they could obviously room share longer if necessary. Thoughts?