Yes, expect cramps during clen.
Anyway when to use it depends on what kind of diet you're on.
If you use your last weeks of cycle for cutting (winny is ok for that purpose) I would use clen during the cycle (2 weeks on, 2 weeks off) using anticatabolic effect from Winstrol (winny) (cause, despite what many say, clen does not have any anticatabolic effect on me. Good fatburner, but that's all I had)