Assuming I went back to age 15 or so... I think Past Me would think, "Hmm, you mean I have to wait THAT much longer until I'll be a lawyer?" Past Me would also want to know how the hell to talk to women, when he learns to cook, and why Present Me doesn't have a "frustration-at-self"-based berserk button.
In short, Past Me would look at Present Me and hit him up for ideas while wondering why it took so long to get where Past Me thought he was going. If he was paying attention, he might realise that he'd learn a lot more if he just shut up every now and then, and that although he'd have a monkey on his back about always being second-best for a LONG time to come yet, it would end eventually.