Because I want to get the interview when I am in Alaska.
If you have a very specific time slot you need to meet, you definitely need to start the process as soon as possible. Slots change all the time as applicants' plans are amended, release times are variable depending on the logistics of the individual station, but by having as much time as possible to grab something you give yourself the best chance of it being in the right place at the right time.
Note that the 5 year validity period only begins after the interview, not from the time of application, and actually only expires on your following birthday, iirc.