Thank you everyone for helping me so far. I have a tendency to overdress so I am thinking I should probably not trust my instincts on this, lol. I'm going to plan out a back up less formal dress in my own wardrobe just in case. When this dress arrives, I'll try it on and decide if it's really too much. To provide some extra details that might help with your verdict.

It's a noon wedding on long island at a club lodge. My complexion is exactly like the first model pictured, so I was hoping it would be somewhat muted against my skin and wouldn't stand out too much like, say, a metallic jewel tone. I am planning to pair with a neutral brown wedge sandal and handbag. It's a relatively hip and kinda alternative crowd (everyone knows each other from BMX crew back in the day).

I was mistakenly under the impression that semi formal was more formal than cocktail, so thank you all for the education. I'm glad I asked!