When will the sacrifices resume?
I don't know. According to most authorities we will have to wait till the temple is rebuilt wile others hold that theoretically it can be done before. In practical terms – I doubt. (See Chinuch 440; Drishat Tzion of Rav Kalisher; Chatam Sofer YD 236; Binyan Tzion 2; Tzitz Eliezer 10, 1; and many more)