I don't think you could make a profit at all running before/after school care with an assistant. Ontario only allows 5 kids under age 13. Most areas would charge about $25 day for both before and after care. That would be a maximum of $125 a day coming in...minus taxes, food expenses, other expenses...then to somehow pay 2 people!
You might be able to pull it off on your own...but the assistant wouldn't make it feasible. Not to mention 5 school age kids do not really need 2 adults watching them!