for me there was no easy transition lol it was a CRAZY time and still is.
DD would get up at night wondering why the baby was crying....seeks way more attention. But thankfully the regression in going potty has not come!
I would just talk talk talk to them, let your child know you are still available, if it's just reading a book while you nurse etc.
One piece of advice that someone gave me, was every new milestep that baby made ( like smiling ) ask the older child "did YOU teach her that??!!) make a big deal out of them having a hand in teaching baby.
I also had a friend who was close to dd take a baby doll and show her how to be gentle, and touch baby nicely. It was better than coming from me.
Make sure you discuss what will happen when you are in hosp. That was heartbreaking for my little one that I would not be home to sleep.
All that stuff about giving baby a gift and baby giving big sister a gift did not work for us.... lol... made her more greedy!
Hope all goes smooth! Good luck!