Leaving a seedling in a small cup past the two week mark means the roots have circled the bottom and growth stalls, even though the plant looks fine from above. Indica seedlings put on root mass quickly, so the leaves reaching the rim of the cup is the signal to move up a size. Pictures of what a healthy versus circled root ball looks like at transplant are posted on https://kushindicaseeds.com, along with a pot size progression. Skipping straight to a large pot works too if you water carefully.