I've planted the seed in regular dirt, in a plastic red cup and now there are several leaves ...?

Yes, it's a cannabis sativa plant, and if you want to preach about the legality not a living soul with half a brain for what's actually a considerably important issue for the government and citizens to debate upon cares, anyway ... when exactly should it be moved to an actual pot and what's the best top soil/fertilizer? I don't want the roots to get messed up or have it die.