Calyxoanswered grow question 4 years ago In my experience,, from the day you notice a root or two popping out the drainage holes at the bottom of the pot to about a week later her roots would've filled out the pot well enough to be ready for transplanting to a bigger pot...
To give you a better idea of when to transplant: when growing organically in soil, plants tend to use up most of the nutrients available in the soil after roughly 3 weeks... This period can be stretched by using amended soil with worm castings and slow release fertilizers, but lets use 3 weeks as our base for reasoning...
If a plant uses al available nutrients in 3 weeks time after being planted into a pot,, that would mean that the roots have filled out the pot around the 3 week mark by looking for nutrients to absorb and would then be ready for transplant to the next size pot.
So I'd say if she's been in the cup for about 3 weeks,, her rootball should be ready for a transplant!
Hope this helps! And good luck... She looks very healthy so far!! 😁