Also, let's not forget the free levels.
DKs are a free team, you can grant them 20 levels from 60 to 80.
For every 2 teams you get another free team.

So level the standard way paladins, druids and monks (because they have all 3 roles: heals, dps, tank).
And then grant DKs 20 levels. You are now left with 20 + 40 + 40 levels to grant.
Level shamans and wars to 30 first. Then grant them the remaining 100 levels.

So you can get 6 teams in like 3-4 weeks or casual play.