Is there a time schedule for the ferry?

Yes, you can go to the WSF website (via WSDOT) and look one up. Or you can find a printed schedule at any ferry terminal.

The schedule for the ferry to Edmonds can be found here: https://www.wsdot.com/ferries/schedule/scheduledetailbyroute.aspx?route=ed-king The schedule for the walk-on ferry to Seattle is here: http://www.kitsaptransit.com/service/fast-ferry/kingston-fast-ferry