This is up to you! However, the FreeStyle Libre sensor only holds 8 hours of data. So aim to scan at least every 8 hours otherwise you'll lose your data.
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We recommend scanning when you wake up, before bed, and a few times throughout the day to get an accurate picture of your glucose levels. Make sure your push notifications are on so you don’t forget to scan!

There is no maximum limit to how often you want to scan though, so feel free to do it more often if you'd like to. Your glucose response will be ready around 2 hours after logging the meal and scanning, and you can set the app to send you a reminder when your results are ready.