My son gave me some potato seed tubers when they were on sale price at focus, so they would have been planted latish for their variety - I know one is desiree but can't remember the other one - when would they be ready?
Desiree are a main crop so need a good bit of time in the ground for the crop to bulk up. I probaly wouldn't want to dig them 'till August. I usually reckon June for First earlies, july for Second earlies and August/September for main. The difficulty with growing maincrop is keeping them blight free until they are ready.
Have had such trouble with blight that I have given up growing anything except First earlies. All the books say they won't keep, but they keep much better than spuds that have been blighted.