Schools actually tell you the last date you can take a test for them to accept it. If you take it in August you will be fine since thats a couple months before the most applications are due. Taking it in August also will leave you with enough time for the applications by all accounts.
However, the only issue is if you don't do as well as you hoped and want to take it again you will have to wait another month and that will stress you out delaying and hurting your R1 apps. You would still have plenty of time for R2 which is usually in January for most schools.