How do you get a baby through the clinic waiting room before his vaccines?

Our son has worked out what the clinic is. At his last vaccines he started crying as soon as we parked, cried through the waiting room, and was still upset an hour after we got home. My partner held him for the injection and was shaken for the rest of the day. The next appointment is next week. Is there anything that helped your baby on the day? Timing around naps, feeding just before or after, which parent holds him? I know the injection is a few seconds. It's the forty minutes of waiting before it that I'd like to make easier.