As per the title, how early can I go to extend my marriage extension?

I usually know things like this, but for some reason I'm just not sure at the moment. As I think it's 30 days, but for some reason I have a recollection of being told I was too early and that it's actually 15 days, or something like that (That might have been while I was on an employment extension or for a 90 day report though, I don't know, it's been so long that it's all foggy lol).

Reason being, I need to book a flight, as I'm going to go overseas between the time that I apply for my extension, and the date by which I have to pick it up (I should get a +1 month extension to my existing visa, so I'm hoping to apply 30 days before, leave a few days grace for incase I miss a document or similar, head overseas for 6 weeks and then come back roughly 1 week before the end of the +1 month extension so that I'll have plenty of time to pickup my new visa).

Applications for "extensions of stay" made 30 days in advance are accepted by the majority of immigration offices and a few will accept applications up to 45 days in advance.

30 days and sometimes 45 days at the odd office.

You should be able to apply up to 30 days early for your extension.

I think Amnat Charon immigration will do the 30 day under consideration the date your extension ends. You will have get a single re-entry permit for that 30 days.

45 days in Chiang Rai so I assume it is the same everywhere.

in northaburi,u can renew 30days before expired date only.