Fiction takes a different mindset from nonfiction, because your aim is to create an experience for the reader. However, most fiction includes an informative element as well. You’re introducing your reader to a culture or time period with which he may be unfamiliar for example.
Since fiction requires a different mindset, I like to work on my novels first each day, as soon as I get to my desk, before I do anything else; even before I read my email. I don’t always succeed in ignoring email, sadly. If I can’t work on my fiction before my writing day starts, I work on it at the end of my day.