My advice would be prepare for the unexpected. Anything that involves lots of work/thought I'd get organised now.
The birth may be not what you imagined. My eldest was born 2 months early. We didn't even have a vest for her.
Lack of sleep can make your brain stop working! I mean that in a gentle way; I remember trying to sew some trousers up and I was so tired I forgot how to sew.
The sling works beautifully for some people but not for others.
I suppose what I am unhelpfully trying to say is that it is so different for everyone, that a bit of forward planning can't hurt. If you don't need it- great.
Those people in your life who are scoffing at you- just let it roll over you. It is awful and amazing and some days you can cycle through awful and amazing many times.
For the next baby, I did lots of batch cooking and that, for me, was a great help. I would have a look round, decide what you can do now and get it organised and then you can mentally 'tick it off.'
You aren't being naive- it's just....incomprehensible until you have experienced it.
At 6 months, I was so tired I had to go to the Dr. with heart palpitations. Because my baby was a prem and had breathing issues, I had been surviving on 2-3 hours a sleep for a long time. She's now getting ready to sit her GCSE's and those terrible nights seem a long distance memory.