I've done some research my self in the past as regards the appropriate time to buy, buying new and selling to early is obviously a killer as regards residuals.
But you get the car, spec, model you want and only you have driven it fine if it's a long term thing.
i guess second hand buying is always going to have attached to it the luck of the draw, just make sure you gen up on it, saves a lot of expense and heart ache in the long run.
🐀