Likelihood of getting drug tested



I went to court for petty larceny and got off with probation since this is my first offense. I shoplifted something under 200 dollars and got caught. My question is what is the likelihood of me actually getting drug tested? My probation officer maid me sign a paper that says I agree to be subjected to random drug tests, but she added that it's just part of their process? I do not understand how this works because I have never been in trouble with the law, but I have a problem. about 2 weeks ago, I tried smoking weed. I only went to court 2 days ago and I didnt know this test would be part of the probation. So I am wondering if they will have tested before the THC is out of my system.
Usually those tests are random and you won't know until it's time.
Random means random -- without any prior knowledge/notice of the testing.
Depending upon the type of test, you can test positive for months after use. You are on probation already. Why on earth would you risk it by using any illegal drugs? Just say no.
An important fact - an attempt to reduce THC levels by dilution is detectable. As I'm guessing you have looked up, drinking excessive amounts of water and liquids in order to lower levels and defeat a drug test is one strategy commonly used. It is typically a violation of probation to attempt to dilute in order to defeat drug testing. Proof is another matter but good luck with your chances if you really want to go that route. At this point you're up to the mercy of random drug testing and you'd best stay off the marijuana.