I've put dozens of corals in a 3 month old tank. 3 months is not the problem. I set up a tank at one point because a coral vendor sent my wife the wrong box of corals and fish and she didn't want any of them. Premixed salt water in the tank from my mixing station, with some dry rock, a bottle of biospira, and then about 2 hours later everything was in the tank. The majority of those corals survived long term. Was it a good way to do it? Absolutely not. Is it doable? yes.There is nothting wrong with the tank is too young if you know what you are doing. But there is a huge problem with putting 38 corals into a 30 gal tank which is only 3 months old. You see the different ?
The problem is the aquarist not understanding how to maintain the tank and the corals. The timelines are more about the aquarist learning how things work, and understanding how to recognize signals his animals are giving him, and building the food chains that are necessary to support things. For some people that takes years, for some it takes weeks. The tank is not too young, the aquarist is too inexperienced. If you're still at a point in the hobby where it takes you almost a year in a tank to keep corals alive - you shouldn't be giving people with new tanks advice - because you don't know what you're doing.
And he already has those corals. Telling him he bought them too soon is entirely unhelpful because he doesn't own a time machine. He can't undo that. Yelling "bad dog" isn't doing anything productive. He needs to figure out how to keep them alive, and then get them growing.
So either help with that, or stop trying to stop the discussion. He needs actionable advice - not to be scolded.