To NS via the Cat Ferry

We're heading up in a week and plan on using the Cat out of Portland with our car. I know we have to go through Customs, yet don't really know how much time this is going to take to go through Customs.

Advise please. Try to be first on the CAT or last on.. Assuming you drive off and to Customs and line up to be checked in. Since I'm traveling on a Saturday, I'm expecting a few others doing the same.