garrettlee is right, they should be AT LEAST a year old before breeding. They are way to immature before that, there are health risks, and if too young they are less apt to be able to take care of the chicks properly.
Do things to DISCOURAGE breeding, do not encourage it!!
Before you even THINK about breeding keets, you really need to do tons of research, you'll find there is a lot more to it than you ever realized if it's going to be done right and with less risk to mom and babies.
Here's a little something on determining the age of your budgieshttp://www.budgieplace.com/age.html
Welcome to the forum Lizzyl. Got pics? LOL
Oh, in the future if you have a question, start a new topic. You'll get more replies that way. This is a very old thread.