The quick answer to that is... all over. I've photographed seniors from all over the state of West Virginia and even some out-of-state schools in Ohio, Pennsylvania, Kentucky and even New Mexico. The map below shows most of the areas HMP seniors have traveled from.
Well, pretty far. The furthest we've traveled for senior pictures so far was to Las Vegas. Definitely wouldn't mind doing that again. Just last year (Class of 2016) we also had a couple of shoots in Savannah, Ga.
As of the Class of 2016, the most popular choice was the split session. The split allows for multiple outfit changes divided between in-studio sets and outdoor locations.
First of all, you should expect to have fun. The shoot is very laid back. The only time I get in "panic mode" is that small window of time just before and after the sun goes down and the lighting is just glorious. Aside from that, don't stress about posing. Usually, before I ask anyone to hit a particular pose, I'll try it myself to make sure it doesn't look or feel terrible and it also takes some of the guesswork out for you. Also, I have a tendency to get carried away on shoots and go over on time. So if you have a date or something after senior pics, you'll probably want to let me know that up front.
As soon as possible following your shoot. You definitely don't want to wait until close to the end of the school year to view and order your prints because at that time I'll be buried in desk work trying to crank out print orders ahead of graduation.
The typical timeline is 4-6 weeks. Could be longer if the order is placed during a rush period (either toward the end of school or just before Christmas). Also keep in mind that the more concept-type / photoshop images you have, the longer it will take to complete your order as those images are all custom pieces that sometimes require hours of work for a single image.