I've been taking one 20MG pill a day since March 17th as my Doctor instructed and I still don't feel it and I'm still freaking out seemingly at random.
Antidepressants typically take 3-12 weeks to kick-in. They are not instant meds like aspirin which begin working within an hour. They work by boosting the growth of new brain cells and strengthening interconnects between cells and across brain areas all of which takes time.
Some of the random "freaking out" may be due to the Prozac. Antidepressants often increase anxiety in the first few weeks by increasing serotonin activity, however, this reverses as the brain adjusts to the med.