All of these suggestions are great. Whatever button is the easiest for them to program on their end that translates into synergy to VIEW then EDIT with the encoder.
It should be a 1-2 punch (VIEW.EDIT.SAVE). Literally that easy with regards to editing ms.
I would go as far as paying extra if this custom update happened.
How about this scenario: the first knob change just shows current delay time at display and puts the knob in a "now I'm at the currrent delay time position and I'm ready to change values" state; nothing happens until the second knob change, which actually edit the current parameter.