Hi,
@Heathero , there's a paper at the link below which I found useful when starting out on libre 3 years ago.
As well as being an interesting (but very geeky!) overview of cgm, the main take away point for me from it was that bg and ifg are most likely to be closest early morning after a stable night, so that's usually the best time to check against a bg test so you can see how far or close to real life the sensor is. That helps a lot in interpreting libre scans when bg is moving quickly.
It also helps in knowing when to calibrate third party apps like xDrip+ and Spike if you bling libre with a blucon or miaomiao transmitter.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2903977/