I wouldn't worry about it too much, normally surgeons leave PLENTY of time between cases for those issues, it's also possible that, that 5pm surgery is your surgeon's only surgery that day, and that it's that late because of all the other standard appointments they have with other patients.
My surgery was SUPER early, so I can't talk to that part of the process, but if you are going in for your first WLS, the bypass generally only takes 2-3 hours total to perform. My revision took over 6, but that's because the lapband I was having removed was full encased in scar tissue and took way longer to get out than expected.
Chalk the fears up to the typical pre-surgical jitters.
Congrats and good luck!