There are various factors that will influence your withdrawal period from Prozac. If you have been on the medication for years and are taking a relatively high dosage, it may be more difficult to quit than if you were only taking it for a few months. Generally, the longer you are on a medication, the more difficult it will be to quit, but there are other factors that influence withdrawal as well. The symptoms can be endless and very unpleasant, so cold turkey is not usually advised.. it really does depend on a lot of factors though... how long you have been on the medication, the dosage... physiology. Unless you are on a very low dose, it is not advisable to quit cold turkey. Tapering may be a safer option, although these options should definitely, definitely be discussed with your GP.
To answer your question about feeling the effects when starting use again after stopping for 3 months, it would be hard to say. It takes a long time to leave the system in comparison to similar drugs, however everyone is different (this rule always applies when it comes to meds!) and it really does depend on your dosage, your body, so on and so forth. Sorry I can't be of more help, though I strongly recommend discussing this with your GP to avoid any unwanted effects.
Good luck, and stay safe!