On the length of time to maturity the little squiggle "~" indicates about. There are so many factors that effect the length oif time to maturity, soil temp and moisture being but 2.
On 1st earlies the very early ones such as Swift and Rocket seem to have sacrificed flavour for speed (in my opinion)
I agree with Kestrel as a good second early
I am not sure on the daylength issue
While I am indebted to you for your explanation of "~" it hardly accounts for the considerable difference between the cropping periods of the more recent varieties and your 90 days, even taking minor climatic variations into account, and, of course, Rocket and Swift are not the only varieties which crop in well under your figure, which is precisely why I said it that took no account of modern varieties.
More to the point is your statement as to your uncertainty on the issue of daylength sensitivity. I
am certain, which is why I pointed it out. However, if you are still in doubt, I would suggest that some study of the various reports and papers on photoperiodism, and photoperiodic response in potatoes, which have appeared at regular intervals over the past 60 years, may resolve your uncertainties.
