I got the principal at my local school to send a flyer home with all the kindergarten parents. They were agreeable to it, then the principal left before I could get the material to her. The 2nd principal was more hesitant but I convinced her after I explained the other principal had already agreed to it.

If I was you I would advertise on Kijiji, Craigslist, here and put up notices on lamp posts and fences near where parents do pick up and drop off. I would also focus on one or two schools as it would be physically impossible to juggle that many pick ups. Maybe find out which school does not have their own B&A program and focus on that one or even better, the school the shortest distance from your house. Go to the school during pick up and drop off, chat up parents and hand out cards/flyers. Even if they don't need you, they may know someone who will.

I did a major advertising blitz when I started which included the above as well as hanging out at the park, library etc and chatting up moms. They are your best resource!