Everyone is going to tell you to run it for at least 5 weeks, 6 weeks at most. Everyone is also going to say 20mg is a waste and to start at 30mg. If you're gong to take a cycle support supplement it really isn't necessary to take the milk thistle, since it's already in whichever cycle support you take (I suggest Competitive Edge Labs Cycle Assist pills). I'd suggest DAA to include in your PCT as well. 3g/3g/3g/3g. I was planning on running Havoc's Epistane until I kept constantly reading about people complaining about gyno/gyno flare ups from estrogen rebound after their PCT. I would definitely suggest something like Erase to take care of that. Something like 0/0/3/2/1 should be good. Better safe than sorry. Also take multivitamins and fish oil during cycle and save creatine for PCT.
Btw, are you trying to cut, recomp or bulk?