You didn't say where you were going to Bschool. That will probably have the biggest impact on getting into a strat firm than anything else you can do in the next 6 months. Anything less than top 5 (Europe) or top 10 (US) would make you a long shot by default.
Second, you should do your best to snag an internship with a MC firm during the summer after your 1st year. This is easier to do because firms are more willing to "gamble" on a borderline candidate for an internship vs. a full-time position after graduating.
Third, if you fail to snag an internship, band with fellow "failed" classmates and start your own MC firm over the summer. There are many smaller companies looking for free MBA-student-consultants to do consulting work over 2-3 months. When interviewing, I view these guys in the same light as candidates who interned at MBBB...as it shows initiative/drive, creativity, etc.
I suggest simply enjoying what's left of your life in the 6 months before Bschool. It'll never be same after that.