When dd was born, my dh thought it was really important to get ds a little gift. I didn't feel so strongly about it, but didn't object either. Honestly, I think ds could've taken it or left it.
This time around, we've gotten dd a little book about becoming a big sister because we found that ds (who was the same age when she arrived) really needed more help understanding what little babies need and processing the transition. I had planned on giving it to her before baby comes, but I don't think it will make much sense to her until the concreteness of life with a newborn is in front of her. So, we will give it to her in the early days after baby comes. DS also will get a book as a means of keeping things balanced. But, I am very hesitant to present these gifts immediately after baby's arrival. I'm much more inclined to wait at least until later that day or maybe the next few days. I find that moment of introducing a new sibling to be so fragile and precious, I just don't want to clutter it up with stuff. I'd rather focus on reassuring the older ones of their place with me, passing baby off to Daddy or Grandma or the midwife so that I can snuggle with them and hug them and talk to them about whatever they want to talk about. Or have them hold and meet their brother, whatever they seem to need at that moment.
Oh, and ds (4 1/2 now) also helped me to make a little softie toy from some of his drawings so he will be giving that to baby brother whenever he feels like it. He was pretty excited about making a gift for the baby, but I think that's cause he's older this time and is anticipating this much more!