What works for you? That's the right answer.
Well, not necessarily. If he's not proficient in shooting revolvers, and snubbies in particular, then it's not going to work well for him. Train first, buy second.
Or, if he's like me, buy three, decide he likes something different, buy that, go to training, switch back to one of the first three in the middle of the class, then sell that one after class. Choose another, buy a new one, sell two of the originals, regret that first sale, buy it again, shoot it lots, buy the coolest gun released at SHOT this year, hate it, sell it, and go to training again. Repeat this until I've owned all of those between two and four times and somehow mastered trigger control during all of that. Then suddenly get into revolvers and try to learn to shoot snubby and big bore revolvers. Fifteen years later, settle on a few "social guns" that never go away while the rest of the pool is fluid.
It's cheaper to train first and use one of the instructor's guns, but my way is more fun