If you are going to have it when you apply for an Extension married to Thai, it was valid at immigration not older than a week. But it is probably best to ask at your immigration.
But as I understand and was told by my Thai wife! all Thai citizens should be registered in some Blue House Book somewhere in Thailand. But you can never be completely sure π π
If you have the opportunity, apply for a Non-O retired 90 days before you travel to Thailand if that works for you. It will becomes easier for you! to apply for a one year extension in Thailand.
And also cheaper! using an agent becomes more expensiveπ π