Did I give my friend the right advice?
I believe, believe, and this is the truth. Ok. Your story would be more complete with the provision of supporting information (of course, one that can be shared online). It's your friend and I don't think there could be a problem with that, right. I'm sure you can explain to him the desire to share this with the bitcoin-community.
If you told your friend about bitcoin, it would be wrong to keep silent about the bitcointalk forum. Help him create an account here and let him delve into the basics of BTC. It will be useful for him, because he's are interested in btc, as you say.
500$ for the first investment in bitcoin. Isn't it too risky? And if a newbie friend makes a mistake with the address or something else, it will be a shame. Why not try with a small amount first to practice?
By the way, when did your friend buy btc? Were there high transaction fees back then?