Cpu schedule, removing thread from queue

I'm implementing now CPU schedule algorithms FCFS, SJF and Round Robin. Could somebody tell when process is removed from queue (FCFS,SJF,RR)? I mean, first CPU execute thread and after executing remove开发者_Go百科 from queue or the other way around?

A process (thread) should be removed from the queue immediately prior to execution, then placed back on the scheduling queue once execution is suspended.