One thing you can start preparing for, even before birth of your precious nugget, is the tough questions. From my experience, God will use kiddos as a way of flushing out things you think you believe or know, but really have not wrestled with.
This can be an easy thing to deal with. You can just parrot back the last thing you heard your pastor say or some piece of theology you actually picked up from a movie or greeting card slogan… but be prepared because they keep getting older and better with questions and pointing out holes.
The worst thing that can happen is that a kiddo stops coming to you for questions. This is heartbreaking for me to even write. You want a lifelong relationship where your child knows they can come to you with any question, doubt, issue.
So start to ask God to take you through your “beliefs”. Start to observe lift more and think about it with a fresh set of eyes. Or put a way I heard it a long time ago… throw everything on the floor and ask Jesus to pick up only the pieces he wants you to take with you (man I love that).
I will get you started with one of the earlier topics that started to shake my old theological foundation. Think about what you will say to your nugget the first time they experience a deep sadness from an injustice of this world. Think about the death of someone they know closely. Now, as a pastor it is easy to sit in front of a huge congregation of Evangelical Christians and teach things like “God has a reason for ____” and “His ways are mysterious”. Now picture yourself sitting in front of your kiddo and saying the same thing with a smile. KEY: What type of picture of God does that leave them with?
I am not saying that you have to have all of the answers. My point is that you want to have wrestled with the things you tell your kiddos. You may humbly end up on “I am still wrestling with that”. What I have found important is to take the key things that are foundation points in your life and point to those and let everything else vary. So for me, I believe EVERYTHING I need to know about God comes from Jesus and His life. Second, I believe Free Will is a real thing (and you can’t really have both love/free-will and a God who puppets every action on this earth). By sticking with those foundations, and a quite a few more, plus a huge dash of humility I make it through and have awesome sessions with the kiddos when these questions come up.
More on all this stuff in the future, but for now the big takeaway is to ask God to help you start to identify areas in your worldview that you should wrestle with. Some will become even more firm, others will be wiped away and replaced and some you will wrestle with for years to come. It is a part of the journey and forces us to stay in relationship with our Abba Father… which is a really good thing.