Hi GordonDavid,
Thanks for your inquiry.
Usually, BME688 needs to run in conjunction with BSEC software, and the corresponding calibration completion time varies depending on the selected configuration. Different configuration files have completed the configuration of heating time and temperature for BME688.
You can download BSEC package from https://www.bosch-sensortec.com/software-tools/software/bme688-software and refer to the integration guide.
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