To set default workflows for creating documents, go to File > Maintenance > Document Management > Templates.
All document templates are listed in the grid. To set a default workflow for a template, use the drop down field in the Workflow column to select the relevant workflow.
If the Workflow column is not shown in the grid, right click in the header row and select Field Chooser. Drag and drop the Workflow field to the position on the header row that you want.
When a user (or another workflow) creates a document using the template, the workflow will be automatically started.