The wait for the show is because it takes a long time to make each episode because of the way it is made.
The company behind Wallace and Gromit and Shaun the Sheep are called Aardman Animations and they make their films using plasticine models.
The models have to be moved by hand for every single frame of the shows, and with 24 frames for every second you see on screen, it can take ages to finish an episode.