The usual recommendation and what I do is to raise your FC above what you normally would BEFORE having a large number of people in the pool. If it's just a couple people, no need to go over your normal target numbers.
For instance, I have a minimum FC of 3 ppm. I normally dose daily or every other day, depending on usage, up to 5-6 ppm. Before a large party or similar, I might bring my FC up to 8 or 10 depending on the guests. After the guests leave, it's a good idea to check to see if the FC is still above your minimum and bring it back up if needed.