My guess ( and it's a total guess) would be Saturday as a much busier day to check in. Even though the kids will be off from school parents work schedules dictate when they can take off from work therefore most I think will be Saturday. HtH.
It used to be that Friday and Saturday check-ins were both light days in the DVC world, with Sunday being the busiest. This was due to the high points imbalance in charging about twice as many points per night on Friday and Saturday as the other 5 days of the week.
Since they've eased off of the point requirements for the weekend, my guess is that Friday would be a bit busier. But that's purely a guess.