Well then, the one thing you obviously have going for you is.....time. However, without already being qualified in a trade, I don't truly know if you can perform an OT, without first finding out if you qualify for your original trade. The second issue is that the Fire Service is also rather backed up with a large waiting list. I'd speculate that, on average, the personnel awaiting for the Fire Service is approximately a year. After all, even back in 1989/90, I had to wait 8 months.....and that was long before PRETC existed. I would imagine that you likely have some personnel awaiting FF trg serving with PRETC right now.
In retrospect, being so new to the CF, I do know that you'd be of more interest to the Fire Service. However, with no FF background mentioned, it may be difficult to compete against others. You see, there is such an interest in this trade, that the recruiters can afford to be particular in who they choose. Although the prerequisite for joining the Fire Service is minimal, there does seem to be a tendency to prefer certain qualifications (ie: Firefighter Level II). I know that if
KinCanucks is reading this, he can likely weigh in on it with more accuracy.
Either way, you won't know unless you try. The bright side is that, the closer you are to your "20" (or should I say "25") the less interested the Fire Service is in you.
Good Luck