Get out all the baby gear. With your second kid, you already know you have many of the items you need. You know the swing is in a box somewhere, and the bouncy seat is mostly put together, but make sure you leave time to wash and reassemble these items! I was also very glad to do this in advance because you can go ahead and put these items out so your other little one can become familiar with the new gear. My 2 year old has been very interested in the new gear we have set out. Each time we set out something new I have talked with him about what the baby will be using it for. ("This is the baby's swing. He can sit in it while we play cars." "This is the baby's carseat. He will get to sit with you in the back seat so you have a buddy now when we go to the store!" ETC.)
Pack your hospital bags. That means one for you and one for your husband who you will probably have to force to pack, but the last thing I would want to do while having contractions is tell my husband what he needs to bring. I would also recommend putting together a little comfort bag for your first baby. (Books about the new baby, a book with your voice recording, ultrasound pictures, Big Bro or Sis outfit, etc.)
Buy a Present from baby to big bro or sis. We plan on having Aiden meet his brother at the hospital and we want to make the transition as smooth as possible so we bought a gift that we can give him from his baby brother. He loves cars so we bought him a car carrying case with a built in racing ramp and we bought a few new cars for him to put in it. We are hoping that 1.) He will love it and 2.) He can play with it at the hospital as an added bonus.
Prep some freezer meals. Here are a few Tried and True freezer Meals I made the first time around. Or if you're just too tired to make your own, buy some. Trader Joe's freezer meals are pretty healthy, inexpensive and delicious so I stocked up on some of those to have on hand as well.
Clean. No one wants to bring a fresh newborn home to a dirty house so make sure the areas baby will be in (especially where they will be sleeping) are clean. Your pregnant self may be cursing as you are bending over scrubbing things, but you will be glad you did it when you come home to a clean space. And honestly, if you don't have the energy to clean, ask for help!
Make a Plan for childcare if you have to leave the house quickly. This seems obvious right? But when you have another person to care for, you have to plan ahead to help things go as smoothly as possible for them as their little world is about to be rocked. Things like planning ahead some meals they can eat, having the car seat already installed in the car of who is watching them, writing a note about their routines, etc. can make a BIG difference for your little one who will already be missing you.
What other things did you make sure to do before bringing home your babies?