I'm on a non-immigrant O visa. My next 90 day report is Sept 12th, however I'm leaving tomorrow to travel in-country until September 16th. Can I do the report from any province? If not, perhaps they would let me do it early tomorrow August 27th?

My understanding is that you must do it at your home province- Immigration office, and that you can do it within 7 days before or after the actual date, though I personally have never let mine go beyond 90 days. There is also a mail-in option, though that involves a lot of red tape; necessary so that they can not say they didn't receive it on time.

You can report by mail or in person up to 15 day early.

Mailig is not a lot of red tape, it is an easy and simple procedure. Only a very few immigration offices do not allow the mailing of the 90 day report.

My understanding is that you must do it at your home province- Immigration office, and that you can do it within 7 days before or after the actual date, though I personally have never let mine go beyond 90 days. There is also a mail-in option, though that involves a lot of red tape; necessary so that they can not say they didn't receive it on time.

You are right exept that is 15 days before not 7 http://www.immigration.go.th/ The mail in has to be to your home province immigration.

My understanding is that you must do it at your home province- Immigration office, and that you can do it within 7 days before or after the actual date, though I personally have never let mine go beyond 90 days. There is also a mail-in option, though that involves a lot of red tape; necessary so that they can not say they didn't receive it on time.

It does not involve red tape. You send it ems and when it is delivered it is signed for and dated. Takes 1 extra minute at the post office.

Actually in cities you do not even have to visit post office as local Soi mailing shops can send EMS for you and provide the trace number immediately.