3,976. Haircuts the Week of One's Watch

Hilchos Bias HaMikdash 1:12

The kohanim whose watch is on duty on a given week may not cut their hair or wash their clothes that whole week; this is to keep them from entering the Temple disheveled. Rather, they must cut their hair, wash, and clean their clothes before they come to the Temple.

Hilchos Bias HaMikdash 1:13

If a kohein’s watch ends during chol hamoed, he may cut his hair on chol hamoed. [This is normally not permitted, but an exception is made because he wasn’t able before yom tov due to circumstances beyond his control.] However, if his watch ends on erev yom tov, he may only cut his hair on that day alone.