since you last smoked in jan. you were clean until you took those 3 hits. a one time user can show positive for usually 3 to 5 days after use. So i would say if you have a week or so before you have to test, you should drink plenty of water before your test and take some vitamin B and make sure you take your sample in midstream (start peeing in the toilet then take sample then finish in the toilet) and I think you should be fine.
GOOD LUCK