I don't nescaserrily believe the whole 'mature' and 'get a foundation' arguements, I think people say this, so you lift longer, get more experience and learn things along the way, so you won't go into gear unprepared and waste it, or end up in a lot of trouble if you don't know what you're doing, all in all it's the users choice, I don't see how increased protein synthesis/cortisol reduction (effects from gear) and others depending on what type of gear have anything to do with a certain time they should be run, they speed up the process, and prevent catabolism of muscle, so in essence it's just more efficient bodybuilding....
just be sure you're ready, only the user can ultimately make the descision... be confident in when it's time and don't run crazy ass dosages first time, be reasonable, logical, and knowledgable.