Getting ready for the app store! Any tips?

We've been in closed beta for the past 2 months and we're getting geared up towards our app store submission. Currently waiting for this DUNS number... apparently, it can take up to 30 days :( We have all the description, keywords and screenshots ready. Just wondering what was your experience like when submitting to the app store?

P.S: We're building Stadium Live - a social sports app for Gen Z. We're currently in beta so feel free to check it out here: https://testflight.apple.com/join/SJgYHzfc
Use code 'KEVMONEY'