I live in NYC and was convicted of DWI (first offense). I was sentenced in May '10. I have paid all fines and have completed all required courses (as required by DMV, court, and NYS) and am currently maintaining a perfectly clean record with the Interlock program and have had absolutely no run-ins or negative actions during my probation term to date. When is the earliest I can ask for an early discharge from probation?

Depends on how long your probation is for... lets say 1 year. So after you have completed 6 months of your probation you should be able to ask for that early release.

Ask your PO to give you some advise and paperwork on it. :)