Welcome to the Forums and Congratulations on your first Chameleon! You will love the little female carpet. I would not get too worried about having a female over a male. Yes, she will have some more needs because of her ability to lay eggs over a male but don't let that scare you. On the plus side, females show more coloration and can develop these amazing color patterns.
To quickly answer your questions, I believe come carpets can be sexually mature at as young as 3 months old. Does that mean she will lay the first week you have her, most likely no but each chameleon is different so you will just have to keep an eye on her. You should easily be able to notice the changes in her when she is developing eggs and needs to lay.
Make sure she has enough calcium during the development as the eggs will suck it out of her as well as right after she lays to build back up her levels.
Feel free to PM me if you have more questions. Dooley1 (Kevin) is the King/Master/Leader (whatever you want to call him) of carpets and he is always more than willing to help as well!
