Just so you are aware: Part of the Lithium Community 2018 roadmap (we are just finishing Lithium's 2018 year) are improvements in the field of Common Analytics. Part of that package initially planned was also the ability to set up thresholds for metrics to trigger notifications. This hasn't been delivered so far, but before you are building your custom dashboard you might want to think about waiting until our new and updated consolidated roadmap for Lithium + Spredfast gets shared over the coming months to see if platforms enhancements might serve your need.
NB: I haven't seen our new roadmap yet since it's not finalized. So I don't know if this item actually made it into the upcoming plan.