F.J.
My daughter has had 5 heart surgeries. First thing you should know is that every child and every surgery & recovery is different. If everything goes smoothly during the surgery then I would expect your son to be in the PICU for only a few days. After that he should go to the "floor" and you could be home within a week or so. We have always been told at discharge: "activity as tolerated". haha! You never know what silly things these kids are going to try! My daughter was no exception to being determined to do whatever she wanted to NO MATTER WHAT! I would follow her around and try to do things for her and trying to prevent her from climbing onto things, etc.
If you son has a tricycle or bike, you may want to hide it until he is cleared for that type of activity. I always keep a lot of crafts on hand since my daughter is not able to do a lot of activity at this stage in her life.
Where is your son going to have surgery? I live in Tucson and I know the doctors well here. If you are going to Phoenix, I know a couple of moms of CHD kids up there that I can put you in touch with. I am also on several heart support groups if you are interested.
Let me know if there is anything I can help you with. I've been a mom of a child with CHD for almost 20 years! ;-)
~N.