There is no set time limit. Your probation officer will send your file along with the recommendation over to the court liason officer who will talk to the judge when time is available. The judge is still dealing with all the new cases, probation violations, and motions to early terminate - which are probably the least important on their docket. Even your p.o. probable doesn't know for sure. Good luck in getting off!
It really just depends on how busy the judge is and how diligent the judge is in going through motions and things like that. Also, if the court is in a busy trial, it could easily get pushed to the bottom of a stack. There is just no way to say for sure. Every court is different. If you had an attorney doing it for you, the the attorney could go by every so often to see if the Judge had made a deicision and to talk to the Judge about it. Good Luck.