No need to worry, I think the Eastern route for pm classes should have enough (or very close) students already to operate. However, you may not have many replies here since many of them are current students and those parents may not visit BK only.
You may call Kwoon Chung, the school bus company to fax you the route, their number is 2578-1178.
For the current year, it is the first time we have Kowloon School buses. However, it is only available for pm classes this year due to insufficient demand from the am classes' students. There are two routes, one from Kowloon West (Kowloon station, Olympic, and Tsing Yi) and one from Kowloon East (Lam Tin, Yau Tong and TKO).
The Kowloon school buses is on trial basis this year, will have meetings with the school bus company to confirm the arrangement for the next years.