S.H.
My daughter was 3 years old when I was pregnant with my 2nd child, and she turned 4 a couple of months after he was born.
I, from the time I was pregnant with my 2nd child, told my daughter "You are my FIRST baby... and I will always love you no matter what... that is why you are special..." My daughter gets great comfort from hearing that... and even now. Of course I don't "compare" she and her brother or say that in front of my son.. but I have a special phrase with my son too.. saying he is my FIRST son.... and always will be and Mommy loves you etc.
I prepped my daughter and spent a lot of time with her doing that, while I was pregnant.
Some things I did was:
-take her to all my pre-natal appointments. The Doctor encourages this and even taught her how to use the Doppler device on my tummy to 'hear' her brothers heart-beat. She LOVED that.
- I took photos of her very month, as my tummy grew, WITH my tummy or her caressing my tummy. It was special for HER... not for my sake, but for her.
- I spent time explaining to her what a baby is, what they do, how come they cry, how Mommy has to feed him, how baby LOVES HER too, that baby can 'hear' her in my tummy etc. I then gave her confidence in the whole process WITH me being pregnant and having feelings about her brother in my tummy.
_ I let her express ANY feeling, insecurities or worries or great ideas/thoughts about baby. And praised her.
-We bought things for her baby brother together...
- I explained to her that Mommy has to take care of baby in my tummy too... that I have to rest. And we would nap together... she would even tell me "Mommy you need to rest, I'll get a blanket for you..." and she felt "caring" about the whole process and the baby in my tummy. Developing "empathy".
- I let her rub my tummy, sing to it, talk to it, etc. It gave her a connection to her baby brother.
- I made up a "special" nod and hand-shake with my daughter, that only the 2 of us would do... just to check on the other or to 'connect' with each other even if was busy or we were across the room from each other. My daughter LOVED this, and we STILL do that with each other. It is "special" and just between us.
Most importantly...you need to make time for him after baby is home. An "eldest" child has to adapt to their 'new' baby too. They will need even more time and one on one time. A child does not suddenly "become" older just because they are now an "eldest" sibling.... KEEP all "expectations" upon him AGE-appropriate. And, some children will also regress at times. Its okay. An eldest child is not perfect nor "all grown up" by default just because they have a baby sibling. They are STILL just a child, too.
I let my daughter know, that I do NOT "expect" her to be different/better just because she is now the eldest...that she is NOT the "example" for her brother by default of her being the eldest... I know that she is still a child... .and needs Mommy too... that she can tell me anything no matter what and its okay.
Just some quick ideas,
All the best & Congratulations,
Susan