After setup, it is necessary to manually create the database tables required for the Timer Service. WebSphere Application Server provides the DDL for these tables in it's WAS_HOME /Scheduler directory.
The DDL files that should be run are the createTablespaceXXX.ddl and createSchemaXXX.ddl in that order, where XXX is your target database product name.
Each DDL file contains instructions appropriate for running against your target database.