Sorry to hear,
but I don't think the business schools care so much about what company you work for and those you previously worked at as much as what things you picked up in those jobs.
As for test taking times, that's up to personal preference to be honest, and most exams are at 8 AM and I think the later times go away that much quicker. I took my 1st GMAT at 4 PM and will take my 2nd one at 2 PM, but that's because I want an afternoon test and prefer a later exam time. If you wake up consistently at 6 in the morning, then go for the 8 AM exam. If it was me, I may bomb it because I don't like waking up that early, and I start work at 10 AM. For me, the nearest test center is 40 miles away, so it would require me to be up at least three hours before the exam, or in other words, I have to wake up at 5 AM or so to eat, get ready, and commute there.
I think the migraine may have been a bigger factor than what time you took the exam, but if you take it at noon, depending on what time you wake up, you want to make sure you eat a couple hours before the exam, so you won't feel hungry during most of the test, and also make sure that you don't have to take a piss every 15 minutes if you drink a lot of coffee on most mornings.
Most schools don't care how many times you take the exam, especially considering that you aren't applying for Fall 2012. However, if they see that you're getting several scores in the same range and always score there, they will think you maxed out at a certain point, and if your essays and other parts of your application are worse, then that won't look good either.
good luck with the next exam