My question involves criminal law for the state of: Washington

How do i reduce my probation time for an assault misdemeanor charge of "Unwelcome touching". I am in classes now and will complete the 1 year class required next April. But then i still have another 3 and a half years of probation ahead of me. I also want to vacate the sentence and expunge the records also so that i can go to Canada for freely. A lawyer here says he can vacate the sentence for a flat fee of $1400. He says expunging can be done by filling out an WSP form. But what do I need to do to reduce the probation length to time served when the class is done?