How soon before my Non-O visa expires can I apply for an extension, and how can I avoid pitfalls in the process?

One last question. I've just been told that because I'm getting an extension again for my Non-O visa that there is no "under consideration" period and I should get the extension stamped and a re-entry permit granted the same day. If this is true I can fly home a week earlier. Can anyone confirm this?

Unfortunately I decided to wait a few weeks to get a new extension but my mother passed away suddenly 😢. I'm flying home but as funerals in the UK are running behind I'm still hoping to make it for her funeral and have been told I can apply for the extension this Friday so have all the bank statements, condo contract, forms etc ready. I have a copy of an old TM30 I used last time but tried to get a new one from my condo reception but they say the system has not been available for weeks and ti get a new TM 30 from immigration. I've never heard of this before but is it possible they issue them? I thought it was your landlord who gave it out.

I'm also going to ask if they can fast track the "under consideration" period after all my paperwork is accepted. Do you think this will be possible or just wishful thinking. I'm in Chiang Mai by the way.

many thanks in advance.