my Non O visa didn't come on time this time so I come 30 days visa exempt, next day I went to local immigration and extended for 30 days giving you time to get documents sorted, when you get married cert you can go back get another extension for 60 day based on marriage,
Then if you have funds in thai bank extended again for 1 year
make sure you go to government office to make it legal, when I did mine 12 years ago took about a hour.
Don't know if you want to take wife to your country, but if you do translated you married certificate when you get it ,get it stamped, and register your marriage at your embassy, it's hard work if you don't, and want to go down that route