As I understand it, there usually needs to be some event (hitting a ruler with the needle, needle jams, getting a rag sucked into the bobbin area while cleaning) that requires a machine to be retimed. They shouldn't just "drift" into bad timing. You say it's your first quilt - not sure if the machine is brand new, but if so, that should definitely not happen.
I'd suggest contacting APQS for help if you've already retimed it once using their instructions/videos. They are very helpful even if you aren't the original owner with a warranty.