you've mentioned you would like to start team leagues (i'm hoping similar to CSL cus that seems to be the best it can get to a school league) but when do you plan?
If you're waiting for more people... I don't think that's the right way to do it. Many people may not want to participate in 1v1 tournaments where they will be afraid of losing in the first round.
I'm sure if you organize your forums (get the spammers out somehow) or have people email you their teams instead... then things will be much faster. You could start as soon as there are a few teams, even 8 seems like a very strong number. Perhaps even fewer. Because once those team members see that the there is an actual team league, I'm sure that they'll tell their friends about it and those friends will also make teams from their schools. Of course though, if having a league with only a few teams, the "season" should be short so that new teams won't have to wait very long to sign up. If you guys want to you could even slowly add people in and adjust the schedules to make them fit at least somewhat decently and then start once there are a lot of teams (16+?).
TL;DR
Emphasize people on HSL to send their teams to your email, and starting a league ASAP even with only a few teams should speed up the growth by a lot and also make the early stage of the HSL a lot more competitive, interesting, and best of all, fun.
Note: Currently my school, and 2 of my friends' schools already have teams because I told them about it, so yeah. In addition to the 2 I saw on the forums, that's 5. And I'm sure there are a few more teams/schools as seen in the 1v1s, even though they weren't in the Team Listings on the forums.
So pretty much, we probably already have 8 teams ready to go!