Peaks and Big B are correct—no disadvantages at all; you’ll have much better weather at the outset, meaning you’ll make better time, hike later into the day, take fewer days off, fewer zero or town days, etc., you’ll have fewer “short” days beacuse of bad weather, soaked stuff, etc. You’ll probably be able to start out with a few pounds less of clothes and you’ll need to carry less food weight as you’ll make better time at the outset because you’ll be hiking “full” days right away; most February and March hikers have quite a few abbreviated hiking days due to late morning starts, 3PM finishes, etc.
You’ll also be well past the pack of Northbounders, meaning a better chance at a shelter or nice campsite as you’ll be travelling amongst fewer folks. Hostels with limited capacities will almost certainly have space for you if you want.
Statistics I saw at the ATC office yesterday said the average “completion” time for a full-thru hike was 170-175 days the last few years; even if you hike at an AVERAGE pace, you shouldn’t have a problem; if you do fall behind a bit, you’ll have ample oportunities to bump up your pace a bit and gain some time once you’re in Virginia.
Baltimore Jack