Here is the info on seeding right from the atlantatrackclub.org site:
TOP-SEEDED RUNNERS:
Runners who have run a 10K race in the following times on a U.S.A. Track and Field (USATF) certified course on a date after March 1, 2007, qualify for top-seeding.
Open Men: Open (under age 40): 36:30 or faster
Masters Men: (40+) 38:00 or faster
Open Women: Open (under age 40): 40:00 or faster
Masters Women: (40+) 41:30 or faster
SUB-SEEDED (Sub 42 minutes):
All runners (male & female, age 10 & older) who have run a 10K race in 41:59 or faster qualify for sub-seeding. This time must have been run on a U.S.A. Track and Field (USATF) certified course anytime after March 1, 2006.
TIME GROUP 1A (42:00 through 49:59):
All runners (male & female, age 10 and older) who have run a 10K race in 42:00 through 49:59 qualify for Time Group 1-A. This time must have been run on a U.S.A. Track and Field (USATF) certified course anytime after March 1, 2006.
TIME GROUP 1B (50:00 through 54:59):
All runners (male & female, age 10 and older) who have run a 10K race in 50:00 through 54:59 qualify for Time Group 1-B. This time must have been run on a U.S.A. Track and Field (USATF) certified course anytime after March 1, 2006.
In the past, it has typically taken two weeks for the cashed check to show up.
Hope this helps!