5'8 Amateur Comp

Sup.

I'm 170lbs looking to go for my first natural comp after slowly bulking to 185. I've yo-yo dieted my entire life and wanted to put on as much muscle as I can once I stay tighten up my diet and stay in an extended surplus. I have never been over 175lbs.

If you were my build, what would you diet down to for your first comp? I've never been fat, born skinny, lean genetics. Never been more then 15% BF probably. Is 185 a good goal weight in regards to my current build? I don't believe in getting as fat as possible to put on muscle so a slow ride to 185 seems the move.
It would be amazing to be able to get super shredded at 155 but I know I may not be there yet. I am only 20 years old. My goal would be 145-155. Do you think it's possible?

All pictures on my profile are 168-173lbs.

Thanks. And I'm 20 years old.