Some issues to think about.

Theoretically, it's OK to do so. However, there are issues you need to take care of.
1) Can you get a most current proof of employment in August ? (If you use the one you got in May, probably it's too old. Lost of things can happen in 3 months, they will be wondering if you are still employed).
2) Make sure you get you original I797.
3) Can you provide the most recent 2 paystubs in August to show you are still employed and get paid ?