figure any estimate a breeder or seed broker gives you is +/- 1 month, lol.... no, but really 1-2 weeks extra is perfectly normal and much more probably experience for any individual seed. maybe autos are more accuate?
if you dont have one, get a 60x jeweler's loupr or currency magnifying glass etc etc for about $5. some come with a clip you can attach to your phone and take 'macro' shots with it.