What are the chances of getting probation terminated early and getting an expungment?

I was convicted of DUI and Reckless Driving about a year ago. Both were the same incident. I got 5 years informal probation. My question is, what are the chances of getting my probation terminated early and getting the convictions expunged? I'm guessing my chances are slim because only one year has passed but I just wanted to know if it were possible. Since then a lot of positive changes have happened for me. I got hired for a federal job with a lot of responsibility and I have completed all classes, paid all fines and got my license back if that all helps. I have never been arrested for anything else. The main reason I want to get it expunged is because the conviction may prevent me from entering Canada. I'm going to be moving to an area close to the border and I have a lot of family there. I'm afraid I won't be able to visit them. If anyone can answer this for me, thanks.