have discussed this by e-mail too recently (the right click action on tasks of a workflow isn’t very obvious, so users may not understand how to insert a new action at the start of the workflow before the 1st action), but it just came to me that it would be enough to prepend one of those arrow buttons you have to the start of the workflow (always start with an arrow)
that is since pressing that arrow makes space to add a new task (more obvious than the right click on the first action)