Ask HN: Things you wish you knew before having kids?

We are talking about having babies. I love twins but I (male) have no control over it. HN has wide audience who are parents as well. What things we should consider before having kids? We are a middle class income couple living in Seattle. We haven’t bought house yet and unlikely to buy for next several years as we don’t want to spend $250k on down payment.

What books shall I and my wife read? Any videos we should watch? How to prepare mentally for arrival and nurturing of new life?

Please add any resources and suggestions.