Looking good so far man!
I read a lot of comments about things that could have been done better. While it's solid advice, you've got this seed slowly doing its thing and that in itself is all that matters! All I can really say is "remember that less is more"
Assuming you have to do this over again, I'd recommend starting them in smaller cups (with jiffy organic seed starting mix. dirt cheap at wal mart and seeds love it) and to plant it when the taproot is about as long as the seed (though I doubt you'll need to start over. It's looking really good). How's the temperature in your box (just curious).
I'm rooting for you, man. Keep up the good work!