It really depends on the unit, and where you are located. YMV
The max Class A days is something like 14-16 days a month.
That being said, you won't get any taskings until at least you pass basic. You may get to parade with the unit or be part of pat platoon however at my unit we never became part of the "unit" until we passed BMQ and SQ. There is class A available at my unit but it is minimal. There are people who are known to max out most months. Where I am there is Class A in the area, outside of the unit so that is an option however you must:
A) Find out in time
B) Get your name up your chain and to ops.
There is also the option of Class B's, which are more or less contracts for a set period of time. However, most of these are for CPL and above, you will find very little for a Pte (B)/(T). However, there was one guy on my basic who was working class B Monday to Friday, but I'd suggest that's extremely rare.
You can find the list here -> http://armyapp.forces.gc.ca/reo-oer/index.aspx
I am to busy with school to try and do Class A during the week, so I've never really tried. I once got asked if I wanted to go on a tasking, I said yes, "Ok we will call you back on friday". I never got the call back ha.
My unit is similar to 2nd's the taskings from within the unit go down and then people say they are available. If you want Class A/B, outside of the unit you will have to find it your self and then get it up your chain. There is employment opportunities outside of ex's/unit training. But I wouldn't really count on getting much until you are least trade qualified.
Again with everything in the military, your mileage may vary.
But if you want full time/lots of work why not go reg force?