If you have a JIRA issue ticket, but you are not ready to schedule it or assign it to a proper team member who’s actually going to do the work, it is possible to create a Placeholder for the JIRA task.
The easiest way to do this is to drag and drop the task holding the Control key (Command key on Mac).
The system will not schedule this task. The task will be still assigned to the previous assignee. However, the Placeholder that indicates that probably there will be potential work for the particular user will appear on the Timeline.