How do you know when your pet is fully grown?
There is nothing on the site itself that tells you if it’s fully grown.
The artist will usually have info about when it evolves and how many stages it has.
As of now, the max number of stages is three stages, so if the image has changed two times since the start image, you know it’s fully grown.
But not all artists use all three image stages, and it only evolves once or not at all.