@james_s We've been giving f.lux away since 2008 for free. Some of the comments we get from users make it all worthwhile. I regret to say that your comment doesn't fall into that category.
Nevertheless I appreciate you took the time to write to us. Future versions of f.lux will be more customizable, and I hope you'll try it again in the future. For now, there are plenty of clones (even built into the OS) who offer manual timers, and hopefully one of them will offer the features that you are looking for.
(closing this poor tired two year old zombie thread)