Nothing has gone wrong (yet, haha). I’m still in the 5 to 10 day review period.
I was just wondering if anyone has any advice on what I should be doing while I wait! This is my first time submitting something, and I’ve felt so lost since hitting the submit button.
Is there anything I can or should be doing while I wait?
Thanks! I hope this isn’t a dumb question…
Setting up some example files - the more situations you can show your asset working in and supporting the better chance of selling to people in a similar situation.
Working on update 1.1 or 1.2. 
Starting on another asset you’d like to offer, or maybe one that works along side the first asset.
Play some games that you have been wanting to play. Xmas is soon approaching and there will be more games to play!
Work on something creative!
Start planning how you are going to spend all that doe. 
Some more ideas:
Make sure your website is polished.
Make sure your demo scenes are polished.
Make polished YouTube tutorial videos. Check sound levels.
Set up a support ticketing system.
Set up a support forum.
Make sure your support/contact form is solid.
Write a skeleton FAQ. As you answer support questions, add them to the FAQ. This will save you and your customers time and frustration.
Prepare release info for Twitter, Facebook, YouTube, Unity Connect, etc.
Ideally you’ve already done the things above before submitting. But if not, now’s the time to do it so everything’s ready on day one. Good luck!
I’ve been doing some of this, but your list is great, and a welcome addition for me. Thank you!!
@TonyLi Do you have any advice for a support ticketing system? I’ve never used help desk software before, and I know I can’t spend money on it right now
Play some Overwatch? 
I like the open source Mantis Bug Tracker.