Where to connect Metra Antenna Adapter?

[3.7 ZPA]

I really didn't want to create a new thread for this, but after hours of searching, I couldn't quite find the answer to my particular question.

My fiancé bought me a Jensen HU a couple of years ago that I'm just getting around to installing now. I know their quality is kind of dubious, but I'm more concerned with performance than audio. However, I did want something that could play my iPod, so this is the route I opted to take.

Anyway, I have the Metra 70-7553 harness adapter soldered to the head unit's harness already. My question is where the hell do I connect the blue wire for the Metro 40-NI12 antenna adapter? I have seen many threads stating that it should be connected to the blue power ant and amp wire, but I already have the blue/white amp turn-on wire attached to this. Do I have the adapter wired correctly? Please help a complete amateur.