The way, you were doing it was the correct approach.
If you would rather just change the URL, then I believe that is documented here, however, I don't know if that applies to you as I don't know if you've recived your upgrade from 8.1.0 or not.
Typically URL parameters would be sent as you have shown, where a ? mark denotes that parameters follow, and parameters are separated with an &
So for you that would look like /devz17?which=test&when=date where test and date are the string representations of the actual values.