brotherjohn wrote:maybe take a couple short trips to get your feet wet someplace familiar
Can't agree more. The best advice I can give to you is to make smaller trips to cities close-by (in a range of 150 to 300 miles for a start), each time extending the distance. That doesn't only give you a better feeling of how long it will take you to get somewhere, it will also (in case you want to sleep outside) help you estimate which equipment will come in handy (or would have), and which you should leave behind.
I don't know how experienced you are, but in case you're new to all this, this is my advice. If of course you have some experience: calculate how long you can hike per day, account that with the distance and you have the time it will maximum take you - unless you get stuck somewhere. Now use your experience on how good the chances for a lift usually are and take that in account as well. Should give you a good hint. And as long as you know the maximum time you'll need, everything else is not really that neccesary to estimate.