Usually if I miss a few doses, any change in how I feel would be delayed by a week or so. I dunno... the effect of Prozac is pretty subtle for me. Sometimes I'm not sure if it is even doing anything, alteast for my OCD symptoms. Are you sure you're not psyching yourself out, Ananda? Anyhow, I wouldn't think it would take as long to build up as when you first started taking it.