You know what, you have done well so far. A lot of folks have hard times cracking seeds. Is there any drainage in the cup? Just keep that seedling moist and not over watered for another 3 weeks. Then you should be ready to transplant.
The little sprouts may stretch and fall over. You left extra room in the cup! So you can add soil around the stem to support it now or when or if it starts falling over. You can add soil and bury all the way up to the first leaves, the very first round ones.
If not feminized seed you may have to pull a male in late August. Good luck.