Schools do like ECs, supposedly some much more so than others. But you can get into schools without any if you present yourself well. Honestly, I think if you suddenly start doing stuff 5 months before you apply its going to look phony and like you are doing it only for your application not because you care. Its a little late to be starting any new ECs...not to tell you its not a good thing to do but you cant really write an essay about your long time devotion to a certain cause if you just started volunteering for it. If you already do stuff then use that or do more with it.
Dont limit your ECs to just thinking charity/volunteer work. Schools want to see you are a human being not a working machine...obviously dont write about your love of the Grand Theft Auto IV or something like that. If there is something you really love to do in your spare time use that. I think most people can come up with something...
I know I had no organized volunteer work but lots of personal activities, and still managed to get admitted to Kellogg, which has a reputation of being a school that really likes applicants to have lots of involvement. Its all in what you do with your time outside of work and how you present it.
Kellogg Class of 2010...still active and willing to help. However, I do not do profile reviews, don't offer predictions on chances and am far to busy to review essays, so save the energy of writing me a PM seeking help for these. If I don't respond to a PM that is not one of the previously mentioned trash can destined messages, please don't take it personally I get so many messages I have a hard to responding to most. The more interesting, compelling, or humorous you message the more likely I am to respond.