It's the worst part, but for me it felt worse looking back on it than during, it wasn't nice but you just do it.
Although after reading on here I expected a baby that couldn't be put down and although he wasn't a great sleeper, he could be put down and I'd have a rest. But it's totally dependent on your DC.
Things I wish I'd known, these are personal to me but I dont know if others found this too:
Get help whenever you can, say yes to people who offer.
Sometimes you might find it hard to sleep once your baby is asleep. Postnatal insomnia is a thing. Some nights I laid awake for hours unable to sleep. Especially at first when you don't know if they'll be up in 20 minutes of 2 hours. I'd listen to relaxing YouTube videos and tell myself laying down and resting was enough.
Its awful but it doesn't feel that bad physically, in that you do get used to it. I expected to feel bone breakingly tired but it didn't feel that bad physically. In fact I felt worse if I went back to bed and napped then if I just stayed up. So sleeping when the baby sleeps didn't work for me.
It affected my driving, I found it harder to judge the speed of others and make quick decisions.
It ends! It will end!
It's not all negative, I've seen beautiful summer storms roll in and rain pour down, heard owls in the night, so many beautiful dawns, the church near me chims every half an hour so I never felt alone, also spent some lovely quiet time snuggling my newborn in the early days when the days zap by.
If you said to me any child of mine would sleep through after six weeks, I'd have plenty more babies.