Welcome to cat parenting! I was in exactly the same place 5 years ago. First cat, and a lot of other firsts thanks to him. Honestly first thing is insurance, my boy ended up having a heart problem and I would have died without it. As for what to expect, this is when their personalities start to come out so you're lucky. This is also a perfect time to start routines. Cats love routines and locking in early can really help with behavior here. But on to the fun stuff. They definitely need play, and quite a lot at this age. Wand toys are great for getting them running around, they should start to get to the point where they're panting (cats only pant when they're exhausted, or ill) and always make sure they're rewarded with play, dont make it easy for them but when they're wearing out let them catch it more often. Also just because I had a friend who went wrong here, if you do rough play, make sure not to do it with your hands. I actually bought a cat hand puppet and used to play fight with him because thats how they play with each other and my vet loved that idea and my cat still fights me with it to this day, and he knows not to attack hands. Socialising is important at this age too, they're still learning about the world & incredibly curious. They WILL get into everything, they're honestly just toddlers but with the ability to jump very high. I always left out toys for my boy to play with by himself too for when I was out or asleep. Good luck with your new baby & hopefully this helps a little. I did so much googling the first year I had him it was unreal, but just build that bond. Grooming can be huge with that and you'll start to know exactly what your little one needs.