In the settings on your phone under something like connections, data usage, billing cycle and data warning, you’ll see this something like the picture below.

You need to ensure that the billing cycle date on your phone matches that of your Koodo account in order to properly track things if you want to do so on your phone.

Alternatively, the Koodo website will always have the most up to date, accurate reporting on your usage.
 

As for when your data resets, that will be at midnight on the final day of your billing cycle.