If I obtain a 90 day Non O from London when it comes to extending this at Udon for a year will the ฿800000 need to be in the bank on the day I apply for tge extension or for 2 months before?

2 months prior

Obviously you have a Thai bank account in your name only? 

7 minutes ago, DrJack54 said:

2 months prior

Obviously you have a Thai bank account in your name only? 

Yes have had various Bangkok bank accounts for 25 + years.

As the Non O has been issued already am I right to assume that I can go and extend a few days before the expiry date and there is no under consideration period.

10 minutes ago, mlkik said:

As the Non O has been issued already am I right to assume that I can go and extend a few days before the expiry date and there is no under consideration period.

Don't understand.

Your non O visa will have a validity period to enter Thailand.

 

If you enter Thailand in that period you will be given a 90 day permission of stay.

 

In the last 30 days apply for extension with the 800k having been in bank for 2 months +

1 hour ago, mlkik said:

As the Non O has been issued already am I right to assume that I can go and extend a few days before the expiry date and there is no under consideration period.

 

Yes, correct.