@chai2,
I must be related to Wally. My mother was a similar type, she arrived everywhere at least an hour early.
Leaving early to counteract any traffiic troubles whch may arise isn't a big deal, there can be many delay factors in that great a dstance (three and a half hr. drive) especially with weekend traffic. Just enjoy the drive there, arrive in the area early, visit a park, visit a museum, visit a few stores (you can just browse), must be plenty of thngs to eat up an hour or two time of.