There was a good explanation of what to expect on the east coast of the US on the PBS Newshour last night. The segment is 6.45 minutes long and you can replay it here:
https://www.pbs.org/video/they-re-baack-1619552955/, While the normal cycle is 17 years it seems to be getting shorter so that there is also a 14 year cycle now for some of the bugs, One more "benefit" of the changing climate. It's pretty impressive to see a picture of the ground completely covered by bugs at the height of the invasion.