I want to get my brother start 5/3/1. He is 16 years old, has been lifting on and off for a couple months, and is familiar with the movements. I know that conditioning & mobility are very important especially for his age, and I will get him bounding (I am also very young and you once said I should be bounding) and doing Agile 8 every day.
But aside from that, which program would you recommend? The 5/3/1 for Beginners that you outlined in your website, or 5’s Pro with Jokers as recommended in the Beyond? If 5’s Pro, should he do it with the 5/3/1 percentages for every movement or are the percentages different for Bench in the Squat-Bench day, as they are in the 5/3/1 for Beginners?
There’s an article on Jim’s site called Help a Friend Get Stronger. That should answer your questions
After you have read that, understand that the best training you can do as a beginner is training your mind to stay focussed on the task at hand while keeping an eye at the bigger picture. For most beginners, that means not throwing everything out (ie new program, replanned diet, extra volume sessions, extra supplements, ton more conditioning or remove all conditioning) the window because you had a bad week.