Just looking for opinions.
I know not everyone scans but I usually do but wondered if there was an ideal time.
I know the earliest is said to be 4 weeks but do you think that is too early or the best time.
Mine will be 4 weeks/28 days next Friday.

I would speak to the scanner/vet to see what they would suggest.  The scanner I use will scan from 4 weeks with accurate numbers.

Scanners seem to be vary, anything from 28 days to 32 days roughly seem to be the favoured times.