Authors:

Up until the time Turner Broadcasting bought Hanna-Barbera, it was essentially an independent studio whose planning cycle had to be nine months. You got a pickup in January, and you put it on the air in September. That's been the cycle.

"Q&A with Hanna-Barbera president Fred Seibert". Interview with Phil Gallo and Richard Setlowe, variety.com. March 23, 1994.
Up until the time Turner Broadcasting bought Hanna-Barbera, it was essentially an independent studio whose planning cycle had to be nine months. You got a pickup in January, and you put it on the air in September.