This was actually supposed to be a part of yesterday's musings post, but I forgot to include it while I was writing that post.
There are two different approaches to the marathon t-shirt.
When a runner registers, and pays, for a race, and it does not matter if it is a half-marathon, a full marathon, a 10km race, or a 5km race, he gets a runners kit. The kit generally contains a bib for the shirt with the racers number on it, a chip that is either embedded in the bib or to be laced into the shoes for tracking the runner during the race, promotional materials from the various sponsors, and a t-shirt. Depending on the quality of the race, and how much you paid to join, the quality of the shirt varies from being a simple shirt to a high quality runner's shirt.
As I began, there are two different approaches to the marathon t-shirt.
Some look at the shirt as being meant for running the marathon in, or even simply as a gift, with advertising on it, for running the marathon. These people will wear the shirt at any time from the moment they pick up the kit, and often even during the marathon itself.
Others look at the t-shirt as a prize. If you joined the marathon, ran it and completed it, you can wear the t-shirt. Sort of like a badge of honor. The t-shirt shows that you ran this or that marathon.
I am in the group #2 type of person. I will not wear the marathon t-shirt until after I have completed the given race. I have had a shirt or two from races I had to cancel my participation in, that I will not wear, even to this day, because in my mind I did not run the race, and I do not deserve to wear the shirt that says I did. Even though I paid for it.
For example, I registered last year for the Jerusalem Half-Marathon. I don't remember why, but in the end I did not run it. Maybe I was not in the mood, or maybe I was not feeling well. Either way, I did not run it. I have not yet worn the shirt that I received form that race. Over a year later. Now I think I can because I just ran the full Jerusalem marathon, so in my mind I have qualified for the honor of wearing the Jerusalem t-shirt.
At the end of the day it is just a t-shirt, and you can do with it what you want. To me, though, it is a badge of honor and accomplishment.