25 yrs old is prolly ~ right... (in terms of brain development all...) (i think i was 21... so it goes...)
I would say that at the age of 14, very very few people have grown enough or experienced enough in life to handle the trip in a way that's productive and meaningful. Most wouldn't know enough about themselves or the world to use the drugs for anything but recreational "fun." But...that's not to say that ALL 14-year-olds are too immature to experiment with mushrooms. Meth, coke, opiates, hardcore drugs like that, absolutely! But mushrooms? When psychedelics are used with respect they have the ability to take you through parts of your mind you're not aware of, and can let you see the world and existence through a completely new perspective. So here's my advice: Make sure you have researched this drug thoroughly. Continue to learn about it, see if you can get in touch with people who have done it before- the hipforums is good for this- and learn from them! If you decide that you're probably ready for it (there's really no way to tell for sure, just honestly find out if your feelings, thoughts and intuition are all on board), find a good friend you trust or a more experienced person to do it with. Don't do it alone your first time. Also make sure you're safe, prepared, close enough to drinkable water and somewhere you can go to the bathroom but preferably out in nature if it's possible. One thing I can tell you for sure is *there is no harm in waiting* If you have doubts about it or even if you don't, waiting a little longer to do it won't hurt you in any way! I personally did it with a very close friend who had already taken mushrooms a few times and sharing my trip with someone who could comfort me, guide me, give me advice and keep us safe, all while letting me have the freedom I needed was an immensely beautiful experience and made for an incredibly spiritual peak!
I really have no idea how you could be tripping before you down 5 grams. Haha if that's from personal experience I want some of your shrooms. I've downed a hefty dose (over 7 gs), and it still took about 45 minutes to kick in at all (I do have a terribly slow metabolism though). I took my largest dose at 16, my first shroom trip was when I was almost 15. I think if you wait too long to take a psychedelic (twenty something) it could be as bad as taking one while you're still mentally immature. The older you get the more shit you hear, and the more skewed your perspective becomes (if you're fitting in with the larger portion of society at least). Your friend sounds like someone I know. He should definitely not take a large dose (doesn't sound like much of an issue any more), unless you're alright with the possibility that he may try to kill himself. I think you should try an eighth. There's going to be mental strain on you regardless of what age you decide to take them (college kids do plenty of stupid shit on psychs). My one extremely fearful experience with shrooms drastically changed the way I view things. I also believe that ego death on shrooms is much rougher than LSD or DMT, and my one bad trip was worse than anything I've ever come close to experiencing on salvia. I've also had quarters of shrooms that have been much weaker than those crazy, giant, white, "rope" looking shrooms I used to get every weekend. Watch your dose, and realize that shroom potency varies.