This isn't written in stone yet, but it looks like the Milwaukee Bucks will be the Celtics' opponent in the Conference Semi-Finals. After accomplishing a 4-game sweep of the Indiana Pacers, the guys in green should get some rest-and-recovery time prior to the next battle - and they may need that.
Since this question is filling my timeline...while there won't be an official announcement until at least Tuesday, there's no way a Boston-Milwaukee series would start until next weekend, almost definitely Sunday.
Network time slots and building availability run the show.