very hard to give a for sure answer. In my experience and my friends experiences its up to the PO a lot. Some are dicks (or just good at their job) and dont tell you much and call you in when they feel like it. Others are up front and will basically tell you that as long as you dont get arrested they dont care what you do. My friend had one that used to give pretty blatant hints about when he would be testd while others have had the opposite.

Chances are after 6 months of clean urine your PO will go over a plan with you and might say something like, expect some calls, or if it was good news say something like Ill check in with you in a few months. Either way you cant know for sure until later.