Does reaching Velocity Platinum Status changes the status review date?

I currently have Gold status (Velocity) with enough status credits to progress to platinum but required to fly 2 more eligible sectors to gain Platinum. My gold review date is in July 19. If I travel the 2 sectors in May 2019 and am then awarded Platinum will the review date then be reset until May 2020 guaranteeing me Platinum for that new 12 month period?

Yes.