Father of a 2.5 yr old here ... Have a few friends who just had kids as well.. I told them the same shpiel

1. The next few months will be the toughest thing you ever go through (comparable to back to back all nighters in college, but this time it's for a few months)... Esp if you're working and don't have good paternity leave. But after you get over that hump. .... It gets a lot better and now you're in the club where everyone knows what you went through because they've been through it too.
2. If your/your partners parents are in the picture and offer to babysit. Take up the offer. Go have a date night with your partner... It'll relieve a lot of stress
3. If you live in a decent area, go for walks with the little one as often as you can. (in a bassinet/stroller obviously)
4. If you're in a western country... If you ever feel like you're doing too little, the littlest amount of effort on your part gets much more props than the amount of effort. Just being there for your new kid and changing every 10th diaper is doing better than 60% of dads out there.
5. Everyone, and I mean everyone, has amnesia about the next 6ish months. They'll say things like "why are you so tired? I don't understand!" Or "it wasn't that bad when we had kids".... It was. They just blocked it out
6. When the kid gets off milk, any spices yall use usually in cooking. Or just generally like that aren't spicy. Expose it to them ASAP. It does wonders for their pallet and they'll be less picky in a few years
7. Both you and your partner are stressed. You will fight and hate each other. Don't make any big life decisions for the next few months.

Hope this helps... Enjoy the journey.