It's an awesome race (I've run it twice), but the weather can be brutally hot. Since you'll be training all summer, you'll be fine
For me, as a first timer, the best advice I got was to start doing long (10+) runs on the weekends starting around April/May, instead of waiting until officially 17 week plans start in July. It was much easier for me to get acclimated to mileage that way. Also, there is no bad ass feeling quite like rocking 15 miles before work or running your long run through the monuments on a Friday night just trying to get it all in. Man... I sort of want to sign up now
