With both our boys, their hemangiomas started involution around 18 months old. There was a noticeable difference after 6 weeks. Our 3.5 year old still has a few dots leftover from his, but they're fading more each day. We're waiting to see if our youngest's H takes the same course - his is a much bigger H - it's already started to break down, we'll see how long it takes!
Me - Aimee - Spot on liver
Elliot, 9/20/06 - H on back (nearly gone)
Felix, 7/28/08 - H on forehead (in involution)
Taking the 'wait and see' approach, for now.