I'm a current LEAP student in the Materials Science program, I have one more semester before I get my MS. A few pointers about the whole process for your benefit.
Take as many prerequisites as you can at community college! BU is so expensive (even with a scholarship)! $55000 a semester and not to mention the crazy cost of living! I have to pay $1975 for a tiny 1 br for my wife, child, and I. Its nuts! Please go to community college for phase I, it can cost less than $1000 a year. This especially applies to Materials Science because every single class can be taken at a CC. I don't check this account often, but if I happen to see a message I'll send you the required LEAP course list for your major that was recently hidden for no good reason. I've heard from former leapers that you needed to have something like 6 uncompleted undergrad courses to be admitted to LEAP, and maybe that used to be true, but definitely not anymore.
Also, if you happen to get a 1/3 scholarship, they will give some bull that your scholarship is 0.33*tuition, and disregard those other decimals to rip you off of about $100. If you talk to them and insinuate that that's grounds for a class action lawsuit, they'll give it to you because they know it's dishonest.
Use connections and apply for lab assistant positions immediately, it doesn't matter if you have no experience. I am not as bold, and I have passed up a lot of opportunity, but I know people who are getting great experience and connections as soon as they walk through the door.
Lastly, if your advisor tries to tell you that you should retake a course you already have a good grade in, push back, unless you feel you have forgotten the material. My advisor wanted me to retake Diff EQ, and I fought that man till he admitted I didn't actually have to, and I have had no bad consequences.
Bottom line, take CC classes, and get in and out as fast as possible to save $, and make connections and get experience ASAP.