I started really training for it about 2 to 3 months out. What really helped me the most was 6 weeks out from the race on Saturday mornings I went and did my race mileage. So come race day it was just another workout on Saturday and my legs and body were acclimated to the transitions. Sundays were my long bike rides with a short run after and somewhere during the week I threw in another brick workout. Run, bike, run, bike, run, bike and run. The more you get your legs use to the transitions the better off you are.