Hi,
When willing to start a new activity, I just press the start button once, and once the GPS is checked, I press it a second time to really start the activity.
For the last past month, I had some issues with this last action though, and sometimes the watch screen stays frozen, activity does not launch. The only way to access the watch is a forced reset (long press on the Power button till the watch switches off). This issue happens all the time on the start line of races : so I had to start my races even marathon with no watch, which is really problematic.
I would ask for a replacement of my watch - if possible before end of September to be able to have it for my next race !
Thanks.