It's time for class to begin.

该是上课的时候了。

Hurry up it's time for class.

赶快，到了上课的时分了。

Hurry up, it's time for class.

赶快，到了上课的时候了。

It's time for class, hurry up!

上课时间到了，快点！

Time for class but you're late.

是上课时间，但是你迟到了。