how old should she be?

Question
Hi!  I am the proud owner of 2 cats, a male and female.  The female is just turned 4 months, and the male is about 2 weeks younger.  They have not been fixed, as I want to let the female have a litter first.  But I have been raised with dogs, and am new to the whole cat world.  My question is how old should the female be before she has her first litter, ideally?  Thanks :)

Answer
Congrats on your babies!  I understand your desire to see kittens be born and raised.  It is exciting.  But I think you're going to run into a problem, here, to be honest.

First, please reconsider breeding your kitties.  Anything you may have heard about females benefiting from having a litter before they're spayed is false.  Actually, going into heat just once triples her chances of developing mammary cancer.  And the chances triple every time thereafter.  And cats who are unspayed, especially those who become pregnant, often get a deadly uterine infection called pyometra.  Male cats are more likely to spray if they're not neutered, too.

If you really feel there is some need to breed, she should be between one and two years old, and it should not be on her first heat.  The problem here is that your male is likely to sexually mature about 6 months old, and the female is likely to sexually mature by 9 months.  If she gets pregnant at that age, it would be like a 12-year-old child having a baby.  You would probably have to keep them completely separated for several months so that she doesn't get pregnant too young.