can I travel into Canada on my tourist visa and activate my working holiday visa only when I find a job?
Yes but a couple challenges with that 1) you will need to do a flagpole trip to the nearest Canada/US border to activate 2)you will need travel insurance that not only covers you for the initial visit entry but also out into the future to the planned exipiry date of your IEC else your permit will be shortened. Dont know which country you are from but if UK then max insurance you can get is 2 years. 3)you will still need to show proof of funds as well when you activate plus you cannot apply for a SIN which you need to be able work until you have activated so you might still need to convince employers ahead of activating/ getting a SIN.
When you arrive on the visit should the CBSA officer ask about activating just say you plan to do that later and should be fine. Only other issue maybe with the airline travelling on a one way ticket but just show them the POE even if you have no immedate intention of activating.
Based on others on IEC expect finding a job to take a while so plan finances accordingly.