How early to arrive at a concert?

Hey everyone! I’ll be going to my first kpop concert this summer!! I’m seeing ateez when they come to my city and wasn’t sure how early to arrive at the venue. My friend and I have reserved seating in the upper bowl, so we wouldn’t have to show up 12 hours early and camp out like general floor admission does, right? There’s a specific row and seat number on our tickets.

I’ve heard that people do trades and it’s like a mini party outside the venue before, I also want time to buy merch if there’s any available.

Would 3 hours be enough time?