Being on the waitlist means it’s time to focus and put all your energy into your “Plan B” schools. Nothing about getting off the waitlist is in your control. MIT, like any school, will look to see who accepts admission by May 1st. Then it will selectively pick and choose off it’s waitlist to round out the diversity for the incoming class it’s trying to build.
Here’s a link to a great CC discussion on waitlists. Although it’s a few years old, it’s still relevant today and to MIT.
All the best.