ABC will pace its fall launch over the first few weeks of the season, taking advantage of “Dancing With the Stars” to get things rolling.

Net kicks off the first official night of the 2009-10 season, Sept. 21, with its normal Monday sked: the two-hour premiere of “Dancing With the Stars” and the return of “Castle.”

The following night (Sept. 22), a second two-hour “Dancing” will lead into the launch of frosh skein “The Forgotten.” Regular 8 p.m. entry “Shark Tank” will bow the following week, Sept. 29, when “Dancing” collapses into its usual 9 p.m. results show hour.

A one-time “Dancing” results show will air Sept. 23, leading into the premieres of 9 p.m. comedies “Modern Family” and “Cougar Town.” The Alphabet’s other two comedies on the night, “Hank” and “The Middle,” will bow in the 8 p.m. hour on Sept. 30. (A premiere date for Wednesday 10 p.m. drama “Eastwick” is still to be determined.)

Heavily promoted new thriller “Flash Forward” bows on Thursday of premiere week, Sept. 24, leading into the season premiere of “Grey’s Anatomy” at 9 p.m. “Private Practice” hasn’t yet been given a firm launch date.

ABC’s Sunday-night sked begins Sept. 27 with a two-hour “Extreme Makeover: Home Edition” at 7, followed by “Desperate Housewives” at 9. “America’s Funniest Home Videos” is back at 7 p.m. Oct. 4, as “Home Edition” slides back into its 8 p.m. spot, while 10 p.m. entry “Brothers and Sisters” is also still waiting an airdate.

Net will wait until Oct. 9 to get things rolling on Fridays, when “Ugly Betty” returns with a two-hour season premiere. “Supernanny” is back at 8 p.m. on Oct. 16, when “Ugly Betty” moves to its normal 9 p.m. slot. (“20/20” officially kicks off its season on Sept. 11).

As for Saturdays, ABC’s college football showcase returns on Sept. 5 with Alabama vs. Virginia Tech.