Unofficial Countdown Time adjusted
Bill's original great circle distance between declared points is 21,951 credited nautical miles (nm). He changed his departure airport to Ontario, CA and added San Juan, PR, as an official stop. Now his official declared distance to 21,866 nm. This shorter declared distance reduces his available time to make a new record by about 45 minutes.
He planned to fly those miles in 168 hours. 21,951 / 168 = 130.76 knots. He needs 108.4 knots to break the record. To set a new record, he must better the old one by at least 1%. The 108.4 knots includes that 1%.