TVI in training here!
First step, get him set up for VI services at his school ASAP as well as a low vision appt with an opthalmologist, if you haven't already. He'll need to get a functional vision evaluation and a learning media assessmentfrom a TVI. The FVE and the LMA will determine what his functional/useable vision is (not just in a perfect environment like the drs) and what media he will use to read and write in (print, large print, Braille, etc)
He'll also be evaluated by an orientation and mobilty specialist and this is who will teach him how to get around school, the house, the community (if he's at that level- OM can be exploring the space in front of your face). The OM specialist will also determine if a white cane is needed and fit one for him if determined necessary/teach him how to use it.
Reach out to your state resources. I live in Texas and we have some amazing programs. TSBVI aka Texas school for the blind and visually impaired has summer programs and workshops. There may be some resources near you.

Ultimately, listen to your son. Take into account what he's feeling and what he needs.
This is a huge adjustment and he's not going to adapt over night.

Xoxoxo

Most importantly, be there for him. Do normal family activities. Go on vacations. See movies. Anything he enjoyed before.

Ask the Mobility instructor if you can observe a lesson so you can know what his skills are. Ask for some training on how to guide him.

I have a congenital vision problem. So I don’t know what it’s like to lose vision since I have nothing to compare it to. But I will say this. If your kid is into sports, don’t let sight stop him. Get into VI sports (if there are any in your city). I find that as an adult, it’s harder to integrate fully sighted sports (particularly anything with a ball). But VI sports are fun and are challenging and a good way to meet people.

I know I’m not really answering the question. Best of luck.

Not mentioned yet and I may be biased, But computer literacy is important if not required in today's world and mainstream screen reader software for desktop is terribly expensive($400+ every year or two for an updated version of JAWS). If you run Windows, Look into installing $1, for linux, use fedora or talking arch, If they own a smartphone, Talkback for android and the build in equivalent for Iphone. If your son is able to learn these tools early, he will be able to function online like a sighted person and can function independently in most cases.

As other people have mentioned, there are training programs for people with sight loss. That helped my boyfriend tremendously when he lost his sight at 18. Not only did he learn skills as a blind person, like cooking, computer, cane travel, and wood working, but it also gave him so much confidence back! It is also helpful for him to be around other blind people every once in a while. He went to the Louisiana Center for the Blind and has nothing but good things to say about it. The National Federation of the Blind is also a great organization to become involved in.