They have job fair's all the time. They hire constantly and this is just an oppurtunity to promote jobs. You can be hired on at any time as long as there are positions available. Infact they will be having another at the end of May and one at the end of June.
I just heard on the radio the other day a spiel about jobs at the Magic Kingdom and staring a career there. I figure if they are advertising on the radio they must be in need of CM's. Apply now for the summer season approaching quickly. That way you might get hired on for something you want.