I can speak to the construction at 495/rt 3 in MA into NH as I just drove it yesterday. There is a lot of construction going on in that area, and it is far from complete. Unless they are closing lanes in the daytime, which I do not think they are, you should not have any probs in this area. Since you are leaving at 4:30am, I am guessing you will hit that area at around 10 am. At that hour, you should have no problems at all with traffic. With the construction, and it being the Friday of a long weekend, it will probably be heavy, but won't be all that bad. Your timing is pretty much perfect.
When I was in college, my girlfriend at the time lived just outside of Philly. The route that you described is exactly the route I would take to go see her on weekends. 6 hours of fun-filled driving that was. Ahhhhh, brings back memories....
Good luck on the drive, take your time, get here safe, and ENJOY your vacation!