It is time that i went to pick up my daughter at school. 第一句是现在时,后面定语中的虚拟语气比主句要落 后 一 个 时 态.所以用I went,这个过去式.
It is high time you should go to work.除了落 后 一 个 时 态之外,还可以用would could should 表示虚拟语气.