Originally Posted by LCUF

You can check the timetable here https://www.limousinebus.co.jp/guide/en/timetable/. Limousine Bus is currently operating the line between Haneda and Hilton Tokyo so you should be fine. Others lines like Ginza area are currently suspended so if you search with the timetable you will see something like "Sorry.Could Not Obtain Information. Please Try Again.".

If you want to book ahead, use https://webservice.limousinebus.co.jp/web/en/Top.aspx instead. Looks like Limousine Bus only allow you to book up to a month in advance.

Finally there's real time departure information on how much time it takes vs the usually estimated time here https://www.limousinebus.co.jp/guide/en/realtime/.