My friends and I cruised on the Carnival Princess in June 2007 from Long Beach, CA to Ensenada, Mexico on the 3 night weekend excursion. This was my first time cruising, and I was with 5 cruise experts, so I did not have to worry too much about what to do in confusing situations.
We all live and work in the LA area, so our travel to the embarkation consisted of each of us leaving work early (about noon-ish) and driving to a friend's house in Long Beach to park our cars and get dropped off at the terminal. It was only a 25 minute drive without traffic, and it was nice to have people who had already done this exact drive giving the directions, so there was no need to worry about the details.
When we arrived, we unloaded our bags. And waited. And waited. my more experienced cruising companions were shocked that we weren't assisted by a porter immediately. After about 5 minutes (at least) one of them went looking for a porter and she was told that we needed to carry our bags about 100 feet (not a great distance, but not curbside service) and then wait in line until we could drop the bags on the ground in front of the cart, and hand the porter a tip so that the bags wouldn't be smashed.