Hmm not even that long I'm embarrassed to say as I placed my order on the evening of the 7th August and picked my allocated car up 6 working days later on the 15th August. It was a rush to confirm the PCP, sell my i3 to cover the remaining deposit, confirm the insurance with LV and then take a day off and travel by train to West Drayton to pick it up!
More testing at 70 mph today and on ideal flat road conditions @ 16 DegC reduced consumption to 240 wh/mi so significantly less than my initial figures of ~275 wh/mi in the wet. Tyres set to 43 PSI all round.
If you hadn't realised the Model 3 has a dash cam feature that uses the front and side repeater cameras to record 3 streams. You'll need a half decent USB stick or SD (in adapter) to record the streams and not burn the device out.
Follow the guide below and simply populate one of the front USB ports and the dash cam operates automatically. That also enables the Sentry Mode but it does continually sap power even if it's a trickle. Sentry is activated manually when required.
Simple instructions are format device to Fat32 and create a directory called "TeslaCam".
https://teslatap.com/articles/usb-flash-drives-for-tesla-dashcam/