I’m from the U.S. you can come and go as you please. 90 day report: if you stay 90 days, you have to report. If you leave before 90 days, you don’t have to report. When you come back, starts at day 1 when you enter.
I’ve been here a year and have not reported yet because I’ve left the country 4 times and come back. My first report will be in 3 weeks as I will have been here 90 days straight