Here is the schedule for American Idol:

SEMI FINALS:
Feb 20/21: (12 contestants each night)
Feb 27/Feb 28 (10 contestants each night)
Mar 6/Mar 7: (8 contestants each night)

FINALS:
Mar. 13 (12 contestants)
Mar. 20 (11 contestants)
Mar. 27 (10 contestants)
Apr. 3 ( 9 contestants)
Apr. 10 ( 8 contestants)
Apr. 19 ( 7 contestants)
Apr. 24 ( 6 contestants)
May 01 ( 5 contestants)
May 08 ( 4 contestants)
May 15 ( 3 contestants)
May 22 ( 2 contestants)