Tl202,
It's a difficult question as you have to do what you feel is right for you. However, WSOp recruitment is at at a historic high at the moment due to older platforms being extended and new platforms coming into service. I would imagine that this will be the case for at least a few years.
26 is a good age to join as NCA leaving it until 29 as a direct entrant is leaving it a bit late but that's only my opinion. Applying at 29 will not be detrimental to your chances of being selected, you will still be able to serve a minimum of 12 years which is all the RAF are looking for initially.
I believe that your aptitude scores are valid for one year according to friends who have been through the system recently.
I don't know what your plan is in Canada but as a WSOp you will travel the world anyway, I would reel off a list off places I have visited in the last 12 months but that would just be showing off.
You only live once do what feels right, good luck.