No, TBH, I am really pushing to deal with it now because honestly my fear is (and I don't think this is irrational) if they don't develop the skills to get out of this instant gratification loop now, in just a few short years weed, nicotine and alcohol (or worse) will come in to fill that space very easily. Particularly with how much weed is glamourised in online/"gamer" culture. It's much easier for young teens to hide vaping than it ever was for smoking and I'm uneasily aware that some children at my own school started smoking aged 11. And I really don't want to end up down that road. Dabbling, fine - using it to achieve the same instant gratification and ignore that "I'm bored" feeling - dangerous. So big game plan time really, should have done it earlier, but not too late at 10/11. Using the change to secondary (we are abroad hence change now) as a big pivotal thing. We're doing a lot of talking about the future at the moment - hopes, dreams. He wants a flash car and a house with a pool so I've said OK - why not - at this age, the potential is all still there, and he's a bright boy, he totally has it in his reach to do well but he will need to grow up a bit and develop some skills - patience, grit, hard work. I saw a MN thread a couple of years ago where a poster had decided their ideal lifestyle, costed it out, then used that as a starting point to aim for jobs which would enable that, which I thought was a really different way to go about it, different to the "What's your dream job" kind of approach my generation had, different to the "What are your skills/class/gender suited to?" of my parents' and grandparents' generation.
I don't think you can be passive about it, this is the last big chance. Once they are 13+ you essentially have to ride the wave which is set in motion. So a multi pronged approach:
Limit/monitor screen and device use/activity. There are apps for everything that can track time spent. Let him be bored. It's important.
Talk about device use - acknowledge the positives of it but point out the negatives too. Encourage a dialogue and back and forth thinking about this. Be willing to accept some things he shows you are useful or beneficial to him. At the same time explain to him about the models they use to keep you coming back or glued to it or wanting to spend money. No different than talking about how advertising isn't always true.
Encourage/emphasise/bribe/force if you have to, both social connection outside of school (v useful to act as a "bridge" between schools or bounce between when adolescence causes social friction within one group) and any kind of hobby/interest not tied to a screen - music is good. Or sports/activity, creativity, making stuff.
Set big changes in motion - what's making him unhappy? Why is family life unsettled? Serious, tough, honest chat with self about that. Any underlying issues suspected - anxiety, depression? Anything along the lines of ASD/ADD - private assessment if necessary. IMO you no longer have the 2 years the NHS waiting list dictates.
Model what you want to see - make healthy changes to your own life, lifestyle, situation, mental health. Talk about it so he sees what you are doing.
Encorage/focus on the skill of delayed gratification and persistence, in whichever form it takes. For example we are also focusing on motivating him/helping him develop strategies to save money rather than spend immediately. Future goals etc can come here.