I wouldn't have risked it but they chitted so fast that they were 3-4" and looking very ready to be planted by practically sprouting. Also getting difficult not to damage them when they get that long. I have learned my lesson about ensuring they stay in a dark place until its chitting time and not leaving the box slightly open.
That doesn't sound quite right, unless I have mis-understood you
Storing them in the dark won't work if their dormancy has been broken. They will sprout, and if it is dark the shoots will be long, and white, and brittle. A "chink" of light is not what is making them sprout, its the fact that they have started growing because of temperature.
I think you will be hard pressed to get seed potato tuber that are truly dormant. They will need to come direct from suppliers cold store to you, and go back into cold store when you get them (e.g. fridge)
If they have come from garden centre (say) then they will almost certainly have been warm enough to have broken their dormancy and they will carry on growing when you get them - even in the fridge (albeit slower). That may well be true of an online supplier too - they may have been in a warm area for days being packed etc.
If you put them in the light when you get them they will grow very slowly - particularly if they are kept at low (but not freezing / frosty) temperatures. Mine have been in the unheated conservatory since the last week of January. Their chits are only a few millimetres long