Your probation is over when you are discharged from probation. If you're itching that badly to smoke some more marijuana, sorry, you need to resist a bit longer "just in case."
The review at the end of a deferral is to determine if you should be granted a dismissal. The judge can still conclude that your use of illegal drugs while on probation weighs heavily against dismissal, or even that on full review it justifies declining to dismiss the charge.

