The Delta spike in India (with very little vaccination) was about five weeks from the start to the peak and about 6 weeks from peak to back down. The Delta spike in the UK (with much higher vaccination) was about five weeks from the start to what appears to have been the peak and seems to be headed back down.
The Delta spike in FL started around July 9th. If FL follows the curve of India and the UK, the peak should occur around August 13th. If it follows India on the way down, it should be back to the bottom of the hill around September 24th.
Now, FL is almost 50% fully vaccinated so that may help bring about the peak sooner or suppress it to a lower level. We'll have to see. I would expect, based on India and how the UK is looking, that this spike has burned out by the 50th at WDW.