I'll give you different advice. You mention its going to be your first trip, and not until fall? I'd suggest you take a few short trips before then (1-3 days) to see how you, your bicycle, and your gear work together. You can find what gear works/what doesn't; how far you can really ride in a day; adjust your bicycle's fit for multiple days of riding (quite different than everyday workout riding); and see if you actually like bicycle touring. Just my 2 cents.
Personally I prefer shorter tours (2-5 days) and staying in hotels or hostels. I cant imaging going across the USA in one 3-month trip, but can see doing it a week-at-a-time over the course of a few years.