My dispatch time tracker had always been 100% but now it is 94%. It shows that my order of 3 book flowers was dispatched late but that's not true. I was to dispatch by 4 December but I dispatched earlier on 30 November.
It's reading incomplete data. It should update after 4 December, when it checks at the due date time to see if it was completed, but could take up to 48 hours.
Did you complete the information if not using Etsy labels.
You can mail early but the item does need to be in transit for Aftership to recognize it.
FYI as you reside in the UK make sure to have UK compliant policies including GDPR and 30 day return for non-custom, non-personalized items.