While I have not done an IM, but I have completed several triathlons and long endurance events. Without bragging I am an experienced athlete with a long competition history in triathlon, locally and nationally.
There is no indication in your post your current level of fitness, or if you have done other types of tri, like Sprint, Olympic, or Half Iron events.
There are many factors you need to consider: diet, flexibility, your current fitness base and building an aerobic base and phasing your training up to race date. Swimming, biking and running are individual components that require time and technique. Oh and don't forget living a LIFE including family and work.
With the right preparation the IM becomes a mental event to test your resolve, and your spirit. It is amazing what you can put your body through. Some would argue if you made it through nursing school
you can do a triathlon :-)
As for resources I would recommend Don Fink's book Be Iron Fit. I would be happy to answer your questions off-line at my email which should be on my profile.
Doing triathlon is addictive: bragging rights are forever and you will look at the world in a different way. You will do more in one morning than some folks do all week.