Shouldn't take too long.  

My first surgery to create my pouch she left the whole incision open.  Sewed the muscle cause I could see it during changes of bandages.  Not an ideal way to do it. I hope I never have to go through that ever again.   I was on a wound pump it seems like forever but she also on my third surgery left the stoma hole open which healed pretty quick compared to the big incision.   

Richard. 

I had an open hole from my temporary stoma after takedown. I couldn't see anything, just a gaping hole which I was pretty squeamish about initially. It took several weeks, but each week it got a little smaller. This is the worst of it for your son and it will improve week to week. My scar is not pretty - there's still an indentation and a thick white scar runs across it.  My surgeon recommended the open way of healing as it reduces the risk of infection. He also said that I might consider plastic surgery down the line. It wasn't that important to me so I left it alone.

My Stoma site was also left open to heal; like Lambiepie said, it reduces chances of infection and also scaring, mine took roughly 8 weeks to completely heal.

It's hardly noticeable, no scarring just slight reddening of the area, which if I had a tan, fake or otherwise, it wouldn't be noticeable, although, when standing, I can see a noticeable indentation at the old stoma site.

Same here- about 8 weeks but in my case it left a noticeable scar, although it gets better with time. The Surgeon told me it reduces the chances of an infection. Other than the appearance there should be no issues. I also wouldn't spend any money trying to revise the scar because if he needs a temporary or permanent ileo in the future they will go in through the revised scar and you will be back to square one and it will be a money for nothing situation. 

Lol... I got the money for nothing scenario!   Back to square one. No regrets. 

Richard 

Jeff had a stoma hole as well.  I just asked him and he said about 4-6 weeks.  It is freeky to look at.  Wigged me out for sure!  The scar is a bit nasty.  Here is a thing about scars.  Don't go out in the sun.  For the first year keep it covered.  By next year it will look completely different.  I know this from my open heart surgery my surgeon told me to keep it covered.  I did and you can hardly see the scare.  It's smooth and white looking.  Jeffrey is a bit heavy, so his scar is a little thicker but I think over time it will look better.  Good luck

That is true about scars.  In addition to my 4 bowel surgery scars I have a fresher scar on the bottom of my neck from thyroid cancer surgery in July 2015.  It's barely visible now, but my surgeon said use 70 sunblock on it whenever outside.  I put Aveeno 70 sunblock on it and it really helped I believe.   There are also scar creams. The one recommended on the thyroid cancer board was Mederma to which I had a reaction (possibly from the onion in it), but I had good luck with Scarguard.  These creams supposedly loosen up scar tissue, soften it and ease inflammation.  I used a third cream that had some cortisone in it to reduce swelling and inflammation.  I was very pleased with how my thyroid cancer scar healed- it's certainly better than the stoma scar or the original colectomy scar which stretches from bottom of rib cage to just above the base of my penis.