When is my 90-day report due after entering Thailand on a Non-O marriage visa?

IN theory the way it works out IS your first extension (for the same reason as you got the visa) starts the 90 day count down clock running, SO when you got the 60 day extension it started and your 90 day report would be due 89 days after the date they granted that extension

BUT

Some offices are "counting days different" and start from when you enter (which is not really how it's supposed to go). What I would do IS when you go apply for the yearly extension make sure you ask them WHEN your 90 day report is due. I wish I could be more specific BUT short of going to your immigration office and asking them there's no real way to know when they start counting the 90 days

AND what visa did you enter thailand on?

As a general rule you do a 90 day report when you've been on the same visa entry OR same extension reason when you hit 90 days.