NBC is swapping time periods on Wednesday nights for its two new Fall comedies - 30 Rock and Twenty Good Years - with 30 Rock now slotted to air one-half-hour earlier from 8-8:30 p.m. (ET) while Twenty Good Years will be telecast from 8:30-9 p.m. (ET). In addition, the series premieres of both Twenty Good Years and 30 Rock are now scheduled for Wednesday, October 11.

The announcements were made by Kevin Reilly, President, NBC Entertainment.

"We have the luxury of starting Wednesdays with either of two great new comedies," said Reilly. "We ultimately felt that this change creates better audience flow throughout the night, with Twenty Good Years a more compatible lead-in to The Biggest Loser at 9 p.m. Either way, we can't wait to get started with these terrific programs."

As part of NBC's planned staggered Fall series rollout, Twenty Good Years had previously been announced to debut on Wednesday, October 4 with back-to-back episodes at 8-8:30 p.m. (ET) and 8:30-9 p.m. (ET). 30 Rock had already been set to premiere on October 11.

30 Rock stars Emmy winner Tina Fey (NBC's Saturday Night Live, Mean Girls) as the head writer of a frenetic late-night television variety show (Fey is also the writer and an executive producer with Lorne Michaels). Alec Baldwin (The Aviator, The Cooler) and Tracy Morgan (NBC's Saturday Night Live) also star.

Also rounding out the cast in the half hour comedy are: Jane Krakowski (Ally McBeal) as Jenna Maroney, a sketch actress in the variety show; Scott Adsit (Kicking and Screaming) as Pete Hornberger, the variety show's producer, and Jack McBrayer (Arrested Development) as Kenneth the Page, the over-eager NBC Page -- a highly sought-after entry level position with the network.

30 Rock is executive-produced by Lorne Michaels, Tina Fey, JoAnn Alfano, Marci Klein and David Miner, and is produced by the NBC Universal Television Studio.

Twenty Good Years stars Emmy winner John Lithgow (3rd Rock from the Sun) and Jeffrey Tambor (Arrested Development) as mismatched buddies who realize that life doesn't last forever.

In addition, Twenty Good Years also stars Heather Burns (Bewitched) as John's pregnant daughter Stella along with Jake Sandvig (The Story of Us) as Jeffrey's unmotivated son Hugh.