Can I change my flight after obtaining a Non-O visa based on marriage for Thailand?

Oh and you won't be converting anything once you're here. you will HAVE the "marriage visa" (Non-O based on marriage) 😮

Once you arrive, get stamped in for 90 days, you will wait until you have 30 days or less left, then you will apply for a yearly extension of stay at the immigration office where you live for 1900baht by meeting the proof of 400K baht in a thai bank account in your name only for 2 months before you apply and turning in the correct documentation, copies, photos, etc.

I'd say once you get here, you and your thai wife go to the immigration office and get the hand out listing the requirements so you can make sure you can get the year extension first time you apply for it (y)

once the visa is issued you can change your flight.

Remember though that visa has a validity of 3 months from the date it's issued <- meaning you have to ENTER thailand within that time.