Hey guys, I don't think folks have talked too much about resupply, but I encourage you to take advantage of resupply when you can, especially in the beginning. This can really help you reduce your pack weight. Even two pounds (1 day of food) can make a difference. You can feel it on your back and on your feet.
Everyone's different, but most hikers don't have a huge appetite just starting out. Although it's possible to have a cold snap where it gets down into the 30s (rare), the chance of snow or ice is almost nil. Road crossings and side trails are frequent, so it's not like you would be stranded in deep wilderness if you ran low on food. You should have a little extra margin, but not the margin of food that you would need, say, in the Smokies in February. I have found that 1 1/2 pounds per day is enough for me doing 10-ish miles a day on section-hikes; bigger guys or those with high metabolism might need more. Later on you might require more.
The towns of Blue Ridge Summit/Waynesboro, PA are just a short distance north of the Maryland line, and has resupply. It's a few miles off the Trail. If you look at your guidebooks, you may also see places of lodging in the Cascade, Maryland/Waynesboro, PA area that may pick you up at the Trail, slackpack, or shuttle.
By the way, ATC's shuttle list can be found at
www.appalachiantrail.org/transportation.