I have an order of Anavar prescribed but my doc is leaving it up to me to decide how long to run it...

any suggestions on how I should use this in conjuntion with my TRT?

200mg/wk Test cyp (broken into two 100mg doses)
100mg/wk Test Prop (broken into two 50mg doses)

I was thinking of running anavar for 4 weeks and then taking a break.. or would it be better to run it longer? and is there a point I should stop any way?