The last time I was able to do an online 90 day report was August last year. Since then I have got "ask your Immigration office" and keep getting the same reply... "more than 15 days before due". I have, since August, tried 20 days before, 13 days before and 8 days before on Android phone and on P.C. using different browsers and following Tod's advice. All to no avail.
I'm getting the idea that once you get that notice you are doing some travelling !
Benjamin Hays I did that February 3rd. and the only guess they could come up with was that I have to apply 16+ days before due date, I.e., they don't know.
Then, of course, they got mildly pissed off because I was wasting their time and ushered me out of the office as quickly as possible.
Another case of "I will never admit 'I don't know'".
I did 2 on-line last year then February 3 this year could not and was told to ask immigration, which I did. They guessed I need to do it more than 14 days before, which I knew was b.s..