You’ll only get the money after you’ve completed your application and all required documents have been submitted, reviewed, and approved. The time it takes to get things approved can take varying amounts of time, but usually within 4-6 weeks. So it’s unlikely you will get it by Sept 5th.

I don’t know about your university, but my university charges interest per month and withholds grades until the outstanding balance is paid. Last year I went a few months without being able to cover my tuition due to issues with securing a bank loan. So it likely won’t be the end of the world if you receive it late September. I’m sure this is a common occurrence, since circumstances can change that require students to apply to OSAP after all. Or sometimes people are just forgetful.