Your Felis will mostly grow through role playing. The more rping and literate your rps are, the faster your pet will grow. There is no amount of posts or time that will determine when your pet grows; it all depends on you...and well me...but that last part's not the point.

There are only four stages of the Felis Concolor.
One: Egg
This stage won't last long as long as you keep them warm.
Two: Kit
During this stage your Felis is very curious and loves to interact with others. It can't fly yet, though it may try, but they tire quickly and sleep a lot.
Three: Half-grown
In this stage your Felis is now almost fully grown, but isn't quite there yet. Your Felis can now fly unless you clip their wings ((check items for more info)). The males are now able to breed though the females are not. At this point the Felis now wants to be around its fellow Felises more and forms more bonds, such as a friend ship or a mate.
Four: Adult
At this stage you Felis are now full grown and both male and female can breed.
Here's an outline of each stage.
And here's a colored pick (of my Felis)!
Size comparison:
You
will be rping in this thread. It is how you pets grow. You are welcome to just chat as well, but if you aren't doing an rp post please put it in (()). Your rp post will be in past tens and literate, preferably third person but it's not required. Please don't use chat-speak! Please be polite to the others rping as well, thanks!