Congratulations!
We had my parents over for dinner last night, (early turkey, wife is working a double shift today) and watching the absolute enjoyment on the faces of my mom as our youngest daughter (2.5 yo) drags her around to show her toys, coloring books, etc... And my dad talking to our youngest son (almost 9 yo) about compass directions and how to not get lost in the woods... Was very special to me to see my parents interacting with my kids.
Savor every moment, my parents dont get to see our kids often... Do everything you can to maintain a good relationship with your kids and thier spouses so you get max grandkid time!