Presumably you have no SC's expiring before those August dates and with no eligible sectors you are still red?
If that's the case, after two eligible segments you will be Silver and after four you will be gold as you have already sufficient SC's to qualify both of those levels.
Assuming you earn the 40 SC in flying those eight eligible segments, from the moment your eighth posts you will be Platinum and, as indicated by
@Must...Fly!, you will have this for a further 365 days of Platinum. After then, your 'review' period starts.
For example, if your eighth eligible segment is flown on 15th September and you attain Platinum, you be Platinum until at least after 14th September 2025 and your "review" is complete. You would have until 14th September 2025 to fly a further 8 segments and earn another 800 SC's to retain Platinum which, if achieved, would be until September 2026.