In the config file of i3
you can assign applications to always start on a specific workspace.
Content of movie
For example I assign firefox to workspace 1 in the movie. You can focus on an application as well. Figuring out the class to assign an application to a workspace is done with xprop. We will fix vlc as it will not show up in workspace 7 as it is told to do. We will fix the issue by analyzing the xprop result.