Saturday is designed as a travel/transition day, so if you're going on your summer break, you can leave LMD Friday. It really depends on the program what time that LMD will be, and honestly, most people just leave on Saturday so they have time to pack and put their belongings in storage after they're done. You may be able to get clearer answers from whoever is running the summer program in question.
I personally wouldn't feel comfortable trying to fly out on that Friday unless it was a fairly late flight and I knew I had means to get to the airport.
I would plan to arrive earlier than 7pm, especially if you have to get your things from a storage locker and move across the tzo. Most programs will do the bulk of their inprocessing between 1200-1700 or so, and coming in at night makes for incredibly long transition days.