When does a Marathon start ?

The usual say is that a Marathon starts at 20 Mile mark...
...But while sitting in the waiting room of the hospital of Rybnik, I
could not avoid thinking that a marathon could begin much ahead, with
overcoming all the difficulties which can happen in the training, etc.

So I had the time to think that:
- 5 weeks before, I was in terrific shape and was easily crunching
miles and hard workouts. My dream of running a marathon in 2:35' was
getting close...
- then I woke up one day with inflammation to the sesamoidis which
afflicted me for weeks until I eventually cured it with a cortisone
shot
- my hamstring went out of control, with the tragi-comic even of
getting cramps on a 10k race and even tripping on the finish line
because the leg could not bend anymore. Now I had done some physical
therapy session and deep tissue massage but basically I could not
perform any "faster" workout for weeks and I could not predict how it
could behave on 42km.
- my baby son got a cold and did not let us sleep in the past 4
nights, so I felt really tired

...And I was there, waiting for a doctor to perform a
Cortison+lydocain shot on my ankle which got inflamed 3 days before
(for no apparent reason)... It was a last resort measure.

So all together I thought that I already did have a long way to go
before even maybe able to take the start the day after.

Despite this, I said to myself that I would have anyway tried to run
on 2h35'-36' pace. I must give it anyway a try because of all the
effort done to be there.

So, the day after, I left the HR monitor in the closet , did the usual
pre-race preparation, enjoy the benefit of my "Elite" start bib, and
then go...

Maybe is too tedious to write all the race details (and I am also
typing from a smartphone..), so I just say that I hit half marathon in
1h18'30" and then kept 3'42"/k pace (my target) until 30k.
The ankle was like a stinging needle at every step but I could bear it.

Then..I felt tired, I felt I did not have those energy in the tank to
increase my internal effort and keep the target pace.
The ankle was by than bloody painful, with the medicine numbing effect
completely gone.
So, in short, I had to slow down.
I did not bonk, I did not hit any wall, but I was simply slowing down.
I was no more racing, but only running to the finish line
I was strangely still overtaking other runners who were bonking hard.
Eventually after 2h40'03" I reached the finish line in 23rd place, but
the finish time does not really mattered much.
I could not even walk properly anymore and I felt kind of somehow
disappointed but proud to do it anyway...a Marathon is always a
Marathon

In the next days, once I have a proper PC, I elaborate more, but for
now that's all...