I believe Slave Play runs about 2 hours, sometimes maybe even more if it starts late. And the Wilson isn't particularly close to the Majestic. So no, I don't think you'll be able to make it on time.
My recommendation: don't leave Slave Play early. Better to miss the beginning of Phantom than the end of Slave Play. Especially if you've seen Phantom before, or if you'll have other chances to see it in the future (which is far more likely for Phantom than for Slave Play, considering the respective circumstances of these 2 shows).
But it's also up to you, and how you view the situation: are you more the kind of theatregoer who thinks "This is my only shot to see these shows, so it's better to have a slightly more stressful experience, and potentially miss a small portion at the beginning - because it's in service of maximizing my usage of time"? Or are you more in the camp of "I wont be able to fully enjoy the shows if I'm all frazzled in rushed, and coming in when it's already playing. So it's better to sacrifice 1 of my show slots in order to have a better experience overall?"