This is probably the most important thing. There are phases when your child will refuse to sleep, scream all the time, etc. And in the moment, you start wondering if this is it–are the next 17 years going to be non-stop screaming? And it seems like they will. Then a week later, things change.
Repeat after me: this too shall pass.
Another thing I like to put out there is that you and your partner are about to experience sleep deprivation like you (likely) never have. I read a report that 25% of new parents experience hallucinations due to sleep deprivation (which was very true for me). So get sleep when you can, and try to not have terribly high expectations for yourself–some days, getting through is the best you can do, and that’s okay.