What is the time limit for entering Thailand after receiving a Non-Imm O-A Visa?

Okay, an O-A visa is VALID for a year from the date it is issued. That means you have that long to ENTER thailand and get stamped in for a whole year.

Obviously you want to get the visa as close to when you're coming to thailand as you can so you don't burn down the validity of the visa not being here.

And as may have been pointed out - once the O-A is issued, the money that has been in the home country Bank can be immediately taken out. Because it will not be checked again by anyone. If you go back home in two years you put 800k baht equivalent back in an account for 3 months prior to applying. Or use the 65k equivalent) monthly of money that has hit your home bank account, even if it went on to Thailand. Or in some cases pension / retirement income records are allowed. Check with the Thai Consulate, you deal with.

It is best to time getting the Visa issued, then getting into Thailand asap to maximize total time, of Stay over the two years.

An O-A visa is a multiple entry visa. You will get stamped in for a full year each time you enter Thailand during that first year.

But the available up to 365 days added to the O-A is from the expiration date of visa one year expiration date...i.e ... If you enter 3 months after visa is issued you lose 3 months.

Up to a day before date the visa expires. No other limit. However of you don't enter within the year the the visa expires and you have to start the visa process again. I entered 4 months after visa start date without question.