is it better to cheer someone on at the start or end of triathalon?

I used to run road races and I personally rathered cheering at the end. This is where you had to dig down and find "it" and cheering helped. At the begining your fresh so cheering did not realy help. You also get to have your helpers there for you at the end when you are exhausted...when you really need them.

I agree with the above answer.

I would say the end cause sometimes towards the end you start
giving up on yourself and you need the extra encouragment to give you that push that you need to finish off the race. Cheering at the beginning will only give you a little more confidence but that confidence will wear away quickly

Most importantly… just showing up in the first place. Knowing you’ve got a fan “out there somewhere” can also be a boost.

Most tri’s I enter have the start and finish within walking distance of each other anyway (and those that don’t sometimes offer free spectator shuttle service).

I’d say the middle of the last stage (usually the run) if there was that option.
As Robmandu said… “Most importantly… just showing up in the first place. Knowing you’ve got a fan “out there somewhere” can also be a boost.”