July 1 is the start date and a 90 day subscription received that day will cost $7.50. However, if you had $7.50 paid in as of today, you could not only have the rest of this month but have an additional $3.50 credit (about 40 additional days) or somewhere around November 17.
$30.00 received on July 1 will give you a 12 month subscription through June 30, 07. However, $20.00 received prior to July 1, 06 will give you an additional bonus credit through June 30, 07.
IOW, 20 bucks on June 30 is worth 30 bucks on July 1. Send your money order today.