If you live out by Lancaster (as a point of reference) it's only about an hour longer going the I-81, 77, 26 to 95 route which isn't too bad, considering that hour could easily be eaten up by a delay in DC and even on 95 south of DC in VA. My suggestion would be to check Google Maps before you leave and see what DC traffic looks like. On a Friday I would say the earlier the better if you do go near DC and to be through there by 1p at the latest to be safe so you would want to leave around 11a.