Given the new forecast from the Nantional Hurricane Center I would say that now is the time to start watching Bill a little more closely. It's still not time to rush to the SuperStore and buy batteries and water (you should have those anyway).
The forecast track has been shifting further and further west with each update. This is a little atypical for a storm as they tend to drift a little further east once they make their turn North.
So what should you do now? Nothing. Maybe have a BBQ and make plans for the weekend. Keep an eye on here or even better the Canadian Hurricane Centre. As National Hurricane Center's forecaster Blake said in his 5pm discussion:
THIS IS A GOOD TIME TO POINT OUT THAT THERE IS A LOT OF UNCERTAINTY IN THE LONG-RANGE TROPICAL CYCLONE FORECAST AND ONE SHOULD NOT FOCUS ON THE EXACT TRACK AT THOSE TIME PERIODS.