Let me preface this by saying again that this was not only my first marathon, but also my first race. Unfortunately, thanks to a nagging IT Band problem, I also only trained for 14 weeks. So I was literally "a runner" for only 14 weeks before running in my first marathon.
I know that this is generally a big "no-no", and a lot of running-smart people recommended I drop out or at least cut back to the half. I figured I know my body best though, and decided that I would train as best as I could. If I needed to cutback later, I knew I could and would. Since I was building miles from scratch and recovering from an injury, I didn't run more than 3 miles at a time until mid-February.
So I wouldn't recommend my shotgun marathon approach to anyone else, but only because everybody and every body is different. It worked for me, well enough.