The first and easiest way to check if you are using or even have access to New DSM is to look at your Craft plugin. Click on Craft Manger in your toolbar. Then click on the cog symbol in the top right and go to 'tools'.
If you have New Design System Manager toggled off then you will most likely still be using the legacy version of DSM.
If you have both DSM toggled on, then you can check in sketch to help you differentiate between new and legacy DSM.
Legacy DSM can be accessed via the Craft menu bar on the right hand side of Sketch