@blondie: I have no idea why its at the end of the year/beginning of next year in Canada. one theory i have made myself is that its to "encourage" the pioneers because they only have to be out for about 6 hours during those two weeks, which are pretty cold during that time of year (Especially january), so they get to stay inside during that time instead. also, its easier to take time off during this time with christmas/new years.
for eligibility, you still need 1 year experience befor being invited, but i believe if you start in january you might still be eligible. so you need to start before or during January 2013 to be eligible for December 2013/January 2014 school, before or during January 2014 for December 2014/JAnuary 2015, etc. so those who start in february have the longest wait.