Trigger alert based on cumulative data.

I manage an Inbound SDR Team. We make the first contact to inbound leads. We aim to contact them in the first 15 minutes. 

My team has a daily lead capacity.  Sometimes we receive more leads than our capacity and our response time gets slower. 

I need to receive an alert when the amount of leads is over a threshold so I can speak quickly with my Marketing team to slow down the campaigns.