campden tab, and when to add

So I have a 5 gallon batch about to leave primary and sit on fruit and/ or spices for a bit of time. My first question is how do you guys treat the fruit you are going to add to your meads. I was told that it's one tab per gallon, and to treat the fruit 24 hours prior to adding the must to my fruit. Now here is another question, if my gravity is fine when I'm about to add fruit, couldn't I just add the fruit then add a throw the tab in then? Obviously it would kill anything on the fruit, plus my yeast, which would be fine since I didn't want it to ferment any more.

Generally, it is no problem to add the fruit and add the Campden tablets at the same time. Between the alcohol content and the SO2, most spoilage organisms will be killed.

Your yeast, on the other hand, will not be killed by Campden tablets, and may start fermenting the fruit if they haven't reach their alcohol tolerance. In order to ensure yeast don't reactivate, you need Campden tablets (KMeta) plus potassium sorbate.