You'd need to talk to an instructor. Different schools/flight clubs do things differently so I can't really say what you'll run into. I was taught by a country pilot out of the air force who himself learned to fly from an Alaskan bush pilot, so it had a little more of a unique rote mixed in with it - but after having flown with a dozen-some instructors, each has something to offer. The important thing is to find one you connect with and trust.
Intro flights or discovery flights will not really focus on teaching any of the necessary skills like lessons would, but they do give an overall taste of the experience (as I'm sure you already know) to stoke the interest.
In order to get a student pilot certificate (which is required before you solo, a major requirement and usually done after about 15 hours of instruction) he needs to be at least 16. After soloing there's another 30-50 hours of solo flight and instruction required before taking the exam and practical test - but he'll need to be at least 17 to get the actual PP certificate.
I recommend going up at least once a month for an hour at a time, every 1-2 weeks is a better pace to build proficiency. If too much time lapses between lessons (especially when starting out) a large chunk of time ends up being wasted to just getting back to the level of flying you'd been at last time, without making much real progress forward. Focus less on "building time" at this stage, and more about making each hour meaningful. That may mean waiting a little before starting his training in earnest.
Here's a reasonable write-up I found that lays it out pretty well:
https://flighttrainingcentral.com/2...g-for-young-pilots-how-to-start-flying-early/
Get a logbook (I use
this one) and/or sign up at myflightbook.com to start logging flights.
