4 Is a great number! Congratulations !
You will really enjoy having 4. I have two boys and two girls(15,12,7 & 5) and feel very blessed. It may be hard at first, but just trust you'll get through it. My two youngest, my girls are 17 months apart. It was tough when they were babies ,but now they are almost 6 and 7 and they are best of friends!! Well most of the time (chuckle chuckle).
Congrats & Enjoy,
Rose