In the screenshot you posted, that small 22 is the current temperature in your room as measured by the thermostat. It has nothing to do with your desired temperature or any other settings -- except that if that current temperature falls below 18 (which is your target temperature according to the large number in the middle), the Nest will call for the heat to come on.
If you want your heat to run for up to an hour in the morning but not at any other time, you could set up your schedule to have two set points every day, like:
7AM 20
8AM 8
With this schedule, the Nest will call for heat at 7AM if the room temperature is below 20, and will stop calling for heat once the room reaches 20 if that happens before 8AM. At 8AM and thereafter the Nest won't call for heat at all unless your room temperature drops below 8.
At all times, the small number shown on the dial on the screen will report the current room temperature, regardless of where you are in the schedule or what the target temperature is set to.
