To me that reads like 1409 had an even earlier blossoming, and still holds the record, whereas what's actually reported is this is a new earliest since records began. Granted, it's not much difference between 26th and 27th, (and the peak must surely be at least a little bit subjective?) but if we're disambiguating, why not 'earliest peak since records began, in 812' or similar. At least that's consistent with what's being reported.