I would need more info here. How are you defining a project timeline in Jira today? It sounds like you are trying to use Jira like say MS Project where you have milestones. I'm struggling w/ understanding your question so that I might provide some insights.
Learn how to use two new reports for next-gen projects in Jira Cloud: Cumulative flow diagram and Sprint burndown chart. Ivan Teong, Product Manager, Jira Software, demos the Cumulative ...
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