driving from NYC to Cape Cod on a Saturday?

Hi, we're due to check into our cottage in Truro tomorrow afternoon. My husband is loathe to get up at 6 or 7 a.m. and drive out, just to sit in hours more of traffic, which we fears we'll hit at 10 a.m. or so...any suggestions? Oh and we'll have an 8 year old daughter with us too!
I'm considering finding a cheap hotel for tonight in Rhode Island so we have an easy drive in the morning. But is that really necessary?
If we driving to RI on Saturday morning, leave at 9, spend the afternoon in RI, will the traffic be any more bearable getting onto CC in the later day on Saturday? We've never seen Newport. Thanks for any ideas!