You can preview your document before generating it by using the DocuGen view. You can generate unlimited previews, and they don't count against your quota.

DocuGen item view

1. Add a DocuGen item view to your board
2. The preview will be automatically generated based on a default template
3. You can change the template by going to Settings > Template and replacing the default one.

DocuGen board view

1. Go to your DocuGen board view
2. Go to Preview. The preview will be automatically generated based on the view settings and template. 
3. You can change the template by going to Settings > Template.