@Greg ********
that depends. Many people cannot get a residence certificate for much longer than that.
If you arrive as a tourist and then convert to non-O visa, you cannot do a 90 day report until 90 days after you receive your 1-year extension. So that's probably going to be about 7 months (as long as you don't leave Thailand during this time).
Even if you arrive with a non-O visa you bought from a Thai embassy, you still cannot do a 90 day report until 90 days after you receive the 1-year extension. So at a minimum you're looking at about 5 months.