@nickneyland,

You can show last few set of dataPoints with the help of shift method. Please take a look at this documentation page for step to step tutorial on creating Dynamic Charts.

I would suggest you to store CSV in date-time,value format. Please take a look at this updated JSFiddle for an example with Jun 10 2019 00:00:03 EST,422 format.

—
Vishwas R
Team CanvasJS