This would be my second time. The first startup got started right after my wife gave birth to our second child. And not gonna lie, the challenges introduced by that very nearly wrecked our marriage. But the alternative of a BigCo job would have killed me on the inside, and I'm very lucky to have had my wife's support then and now.
If OP's wife is pregnant I would not recommend switching careers right now. That would be maximizing time away from home when you are needed most. But that's not how I read the OP:
> if I need a full time position once my wife and I start having kids
Sounds like they're still thinking about it, and maybe a few years off.
Very early stage as we're still fundraising for the seed round to start the lab, but most of the core team is already assembled. It's still in stealth mode, and this is supposed to be a pseudonymous HN account so I won't post details here. But you can reach me at the email in my profile if you're curious to know more.
Founding a company isn’t great work/life balance no matter the field, but it is significantly more rewarding in deep tech imho.