I second drummerxyz' response: most important time is the best time for YOU! There are good times where more energy is available (such as 5-7 AM & PM), but that just means you get more "bang for your buck" during those times, and it is useful if you can only do short sets.
But the best time is the best time for you. We only have good, better best in SFQ. So the best, is to have a consistent time for your practice every day. But it is still good to practice whenever you can. And as drummer said, there are little "buffer zones" that are best to keep like 30 minutes before and after eating, sex, going to bathroom, other kinds of exercise or energy practices, etc.
And again, keeping those boundaries is "best", but it is still good to "violate" those boundaries, if that will make sure you get your practice in that day.
Hope that helps.
