If you stay in Keio Plaza, you can check with the staff in the hotel, I remember is around 8:00 a.m. somthing in the morning, it also has return bus from Disneyland to Keio Plaza Hotel and Shinjuku, departure from Disneyland to Shinjuku is around 9:00 p.m., all my information was left at home, I can remember this only. Hope can help.
Leave from Keio Plaza Hotel ( when the parks open at 8:00a.m.)
> 06:30 a.m.
> 09:00 a.m.
> 12:30 p.m.
Leave from Keio Plaza Hotel ( when the parks open at 9:00a.m. or
>10:00a.m.)
> 07:30 a.m.
> 10:00 a.m.
> 01:30 p.m.
Leave from Tokyo Disney Sea ----> from Tokyo Disney Land
> 04:00 p.m. ------------------------ 04:15 p.m.
> 07:05 p.m.------------------------- 07:20 p.m.
> 10:25 p.m.------------------------- 10:40 p.m.