I started young with my boys, some would call it brainwashing I guess. Whatever it was, it seemed to work. I think my two youngest were 4-5 years old when i asked them my first question. The conversation went like this. We were in my kitchen, I had just given them a choclate chip cookie....
me: Ok boys, say you meet a very nice girl when you are much older.
them: Yes mommy
me: you bring them home and introduce them to mommy.
them: yes mommy
me: but the girl does not really like mommy, what should you do?
them: we don't know mommy
me: never bring them home again and make it the last time you date them.
them: ok mommy.
I also told them:
me: so you see this pretty girl,
them: yes mommy
me: see how they are dressed and ask yourself " can I afford them:?
them: why mommy
me: if you cannot afford their outfit, you are not going to be able to afford them when you marry them either.
Another conversation.
me: Boys, if you feel like you can afford them, then you need to find out do they really love Jesus. This is very important.
them: okay mommy
me: boys, you need to know that they really love Jesus, just like you do.
them: okay mommy
Continuing on this topic
me: boys, the girl needs to help you become the best man you can be. She needs to cheer for you and believe in you when no one else does. She should speak respectfully to you and treat you with kindness right from the start.
them: okay mommy
Lastly:
me: boys, you need to love them the way daddy loves me. You need to stand by her, treat her like the gift that she is. You need to be faithful to her and honour her in every way. Okay boys?
them: yes mommy
This conversation continued for years to come. It is not a perfect method, but it was my way. It seems to have worked so far!
I remember one time one of the boys was interested in a girl who wore less clothing in the daytime then I wear at night. I asked this teenage son " could you bring her to the farm to meet Oma and Opa?' He thought about it for a moment, "no mom, that would be embarrassing." That ended it even if she was beautiful and claimed to be a follower of Jesus.
The best thing a parent to be with their children is not be afraid to be honest, speak when it seems right and be good at listening. It helps if we apoligize when we blow it also. Lastly, when kids are young they have much more willingness to listen. When they become teens or even in their twenties, you only have a sentence. They don't like lectures though we love to give them, Makes your few words count and pray!