All I know is Kelvim Escobar had surgery to repair a labrum tear in July 2008. He threw 5 innings in the minors, made his first ML appearance 11 months after surgery, threw 5 innings, and was placed back on the DL. He is probably going to start this year on the DL this year for the Mets because his arm is still not right.
Bedard's doctor said 10-12 months, so the earliest time frame should be June, and that will probably be minor league rehab. That May timeframe was put out by his agent, he shouldn't even think about game action before July. With his injury history, he should not be rushing back because he'll end up tweaking something which will cause a set back. I'd feel less comfortable about this bet if he was targeting a return in early August.