I see. As you are aware, under current Pennsylvania, first degree misdemeanors CANNOT be expunged. As you were informed, the only option would be to file an application or petition with the Pennsylvania Board of Pardons.
A pardon is where the governor (based on the recommendation of the pardon board) grants you the ability to expunge the arrest and conviction. In essence, this is the only way that you would be allowed to obtain an expungment because, without the governor's approval, you are not allowed to have the conviction and arrest expunged.
As for timing, there is no definite time frame. There is also no set rules that the pardon board must follow in determining if they should recommend to the governor that you should be pardoned.
However, there are some "loose" guidelines. For instance, if you have no other criminal history other than the Corruption of Minors conviction, and it has been at least 5 years (which it has been since the conviction occurred in 2009), you are more likely to receive a recommendation for a pardon.
Furthermore, the steps in attempting to obtain a pardon are long and thorough. For instance, around two years after an application is received, you will be interviewed by the pardon board to determine if a pardon is proper for you. They look at things such as: why you want a pardon, what limitations are imposed upon you because of the conviction, what have you done to contribute to society and do you express remorse for committing the Corruption of Minors.
There is a valuable document that explains: how to obtain a pardon and what the application process entails. If you would like, I can attach a link to the document so you can keep it for your records and refer to it throughout your application process.
It is unfortunate that Pennsylvania laws make it difficult to obtain an expungement. However, you still may be able to obtain one ONLY IF you receive a pardon from the governor, which will require you to go through the pardon application and process.