I saw a solo cruiser sitting by himself at a two-top during early dining. You don't have to sit with others.
If you eat at 6:45 p.m., you can make the late show. If the early showtime is 7:00 p.m., you won't make it. If it's 7:30 p.m., you might make it, but probably not.
You'll be fine in that attire for formal night. Have fun!