I just did my first 90day report, but realize now that because I did it 8 days before 90days, now I am supposed to do it again on April 15th, while my DTV stamp expires April 23rd.
So it seems it would have been better to do it exactly at 90 days to stay the maximum days while only 90 day reporting 1 time.
Online reporting was rejected so I went in person. I am not sure if I will be accepted in the future.