Nosey has hit the nail on the head here.
You will be waiting along time before a fulltime base is available for you.
As a S/O temp bases are available for a 2month stint at a time. You then require 4months back in HKG before you are allegible for another base. Temp bases come up rather frequently, but to have a Canadian Temp base you need to be on the B777. But then you could take a temp base anywhere in NA and commute back home.
You need to have done 1 year service (probabtion) before taking a temp base.