Welcome to the club and Congratulations!
I'm a 28yo SAHM of 3. I had my first when I was 24 so I've got a pretty good idea of how you're feeling. My best advice is to relax as much as you can now, because it will be some time before you'll even get to think the word again ;)
I absolutely love being a SAHM (most days LOL!). I'm sure you will too. Try to get as much sleep as possible and maintain an open and loving relationship with your husband. Sometimes men can feel left out so try and give your "first big kid" his attention too.
Oh and one more thing, please try to remember that no one is perfect. We all are constantly learning and even if you make some mistakes (we all have) as long as you love your baby you'll be his/her absolute best mom on the planet!
Good Luck! God Bless you and yours,
Feel free to contact me any time, ____@____.com
K.