I had three children in 3 1/2 years. I will say this...it was much easier to add the third than it was the second child. My first was the center of our world, and her every move and sound fascinated us and she kept our attention to herself. So, of course, when little sister came along when she was 2, she wasn't really thrilled. The simple fact is this, your first child will have to wait for things that were immediate before. Nope, you can't jump rope with him if you are breast-feeding. You may be too tired in the beginning to play tag. I did find that if I did SOMETHING alone with her during the day, it really helped. We played Candy Land at night together.
Also, as I found out, and my Pediatrition friend agrees with, your second child will most likely be easier and play more on their own. They also learn early that life is not all about them, and sometimes THEY have to wait for attention. However, it's like that for them from the beginning, so they don't have to adjust like your first child.
As for the third child...you have already learned how to split your time pretty well. And the first 2 have adjusted to each other and don't really have a hard time adjusting to yet another sibling. Now my older 2 want me to have another!!!
Anyway, that has been my experience. Of course all children are different. God bless.
J.