Timing is everything.
If you want a simple and convenient run up to the Ironman, sign up one year in advance for a race that occurs before the intense heat of summer. To avoid burnout, start your real preparation about 6 months out when large numbers of your triathlon club will be out in training groups. Oh, and make an effort to be independently wealthy so that work will not interfere with your almighty training calendar.
Or if you like a challenge, pick a late season Ironman
So you can start training 11 months in advance
And so you can train through the heat of summer when no one wants to ride with you
And so you can train through the fall after most of your friends have already shut it down for the year
And so you can peak at the same time that the autumnal acceleration of work duties and trials and receptions is at its most intense.
Oh, and be sure and do it the year that fall temperatures decide never to show up in Houston.
Then you can develop some side skills in addition to swim bike and run such as
1. Eating pre-prepared crap in your car or at your desk
2. Experimenting with sleep deprivation
3. Mental calendarical juggling so that you can keep all or most of your training sessions and still do your doctor's appointments and that lame reception which lasts until 9pm after which you drive home and arrive at 9:45 and turn in 90 minutes later such that you sleep so late you miss your morning swim session (but not so late that you can avoid getting up and going early to the office) which swim session you must now fit in some time later in the day after the bike fit perhaps but before picking up the kid from school for piano lessons because of the spouse is on the scrap book retreat or perhaps this evening or perhaps tomorrow morning before the long run that is moved from Sunday to Saturday in order to run while the kid is at band contest due to the scrap booking retreat and that little thing called parenting.
Given my somewhat timid and bookish nature, I have rarely been accused of having "balls." But right now, I'm pretty sure that whatever balls I have are in the air. I don't relish dropping them.
Ah, December. Glorious December. I can hardly wait.