It does not really matter when you apply the sensor, as long as you have an hour to wait for the initialization period.
Regardless of when you apply the sensor, please avoid showering, going to the sauna or high-intensity exercise right after putting it on to ensure the adhesive has time to properly attach. We also recommend avoiding eating when the sensor is calibrating, to ensure the most accurate readings.
In the Veri team, we prefer inserting the sensor in the evening so that it 'settles in' while we're asleep. This way we also get a full day of monitoring on day 14, and can easily continue with a new sensor without any inconvenience to our day.
The sensor readings can be slightly inaccurate during the first two days from installing it, so having the calibration happen at night time allows for more accurate tracking!