what i mean is you don't need to be in hurry to extend it for a yearly visa as i did it. You can still work with that 3months Non-B visa for 2 and half months afte that you can proceed it for a yearly visa. Just from my experience but you gotta make sure you all ready with the papers and bla bla
It actually depends on the immigration officer( Not the immigration Office). If they like ya when they see you, he/she can give you the green light to proceed it here but from my experience you should have to go out of Thailand and get a New Non- B visa.
FYI:- it's better to go out and get a new Non-B if you can get in Lao or any other Thailand neighbouring countries than tryin change it here coz
1. It will buy you more times
Like you can have another extra 2 months which means after 2 months you can proceed your one year extention visa