@Benjamin *****

oh, sorry, yes, that's correct.

For Bangkok:

I sent one for my daughter 23 days before the due date and the slip came back without any note that it's too early. Last time when the online system didn't work (showing overstay in their system = not updated), I mailed it on -15 with a note explaining the situation. And the slip was sent back with a note saying something like don't be late next time (no fine).

At this moment, I'm still waiting for the slip I mailed on June 14th which is -22 days, delivered to the immigration on -20, the documents I sent wasn't returned telling me it's too early. So I presume they are processing it.

That's my experience, and there's no guarantee it won't get rejected but hope this helps.