I checked your time line.. And I see total time duration b/w your POE and File N-400 is 2 year 9 month.
So can we file N-400 after 2 year 9 month dont we have to wait for 3 year after POE ?
6/10/2017: Green card received.
2/20/2019: File I-751.
2/20/2020: File N-400.