Enhanced search setup - How many characters?

I realized that we can set this up to whatever we want, but for a "best practices", what would those using it recommend? I just installed the add-on, and set mine up at 3 characters, as we have lots of searches that would benefit by this.

I considered setting it at two characters, but not sure if that would benefit the setup or not.
Went back and set this up with two characters. Lightning fast, and very impressed with the search results rendered by the enhanced search, as opposed to the stock search we had been using. Kicking myself for not doing this much sooner.