What day of the week does my goal start?
The answer to this question is... there really isn't one! Beeminder doesn't care what day it is, or when you do the work, or submit data to your goal — as long as you stay on the good side of the yellow brick road every day. If you ever end the day on the bad side of your road, you'll derail.
For example, if you start a "6 workouts per week" goal on Monday, the average pace for this goal would be about 0.86 workouts per day: 6 workouts divided by 7 days. If you do one workout per day for the first six days of the week, you'll earn a day off on Sunday. You can do all 6 workouts on Monday and coast the rest of the week! (Not recommended.) But you can't procrastinate and make up a week's worth of workouts on Friday, because you'll have fallen below the average pace before then.