Its recommended but it doesnt seem to make any difference if you do or not. In fact mine works better when i forget to.I think it's recommended to start the app before each trip to make sure it's connected to the car via Bluetooth.
These are the instructions that show up on MyOpel app: View attachment 141176
What phone do you have, as mine only updated to 1.28.0 yesterday, (Google Pixel 3aXL, Android 11.)App updated again. 1.28.1.
Apple 8 plus. iOS 14. Mine only changed to 1.28.0 very recently as well. There must be more owners badgering them to sort the app out so they're updating it a bit quicker!What phone do you have, as mine only updated to 1.28.0 yesterday, (Google Pixel 3aXL, Android 11.)