How bizarre there are suddenly so many of you expecting twins in the same month! Congratulations!!
I was due with my twins last September, but they came toward the end of August. My son was 5 when they were born, and turned 6 four days later.
I haven't had as much time to spend with him, but it's OK. He needs that time to develop relationships with his new little siblings, and his daddy. Our culture has forgotten how families were designed to work - with multiple children, and Mom dividing her love and time between them all. Everyone learning to spread their love around. The more you give it, the more you have to give!! Be thankful your little firstborns won't live the selfish single-child life that so many kids live in our culture today. My son is on the brink of selfish imp, having such a wide space before we were blessed with siblings for him.
And I'm thankful that I get to home school him, so that we have that time together during the day. I'm sure if he were leaving for school each day we really would be feeling like we didn't get to spend enough time together.
... by the way, be sure to check out "Having Twins, Triplets and More" ... not by Barbara Luke. I can't remember the author's name off hand, but it had quite a bit of AP stuff in there, even mentioning CD, BF and home birthing twins! Great book. I remember -- it's by Elizabeth Noble.