I am doing this right now (paternity). I did what most of the comments suggested: asked someone to take on the essential parts of my role (CTO), and scaled back the non-essentials over the course of a few months.

It’s going extremely well. I think the person who took on my role is doing it better than I used to. A spring clean of responsibilities was helpful and forced us to document / distribute a variety of things that used to fall on me for no good reason.

Feel free to email me if you want to discuss more.

And most importantly, congratulations! You’re going to love it. Whatever you do regarding work, structure it so you don’t have to think about it when you do 2am feeds (because you really won’t want to).