Personally I think it is good to start early - especially if you are handling her. It will be good practise for both of you and you should learn a lot. By the way. I would recommend having someone videotape you in the ring - you can learn a LOT by watching to see how you both did and get a good feel for what you need to work on.
Puppies can and do win. However, a lot depends on YOUR dog. Some dogs take a long, long time to mature - so their head might not have filled out and it might be too long, or they don't have a chest, or any number of reasons. Other dogs mature really young - so they look good from a young age.
Star, my pup, always looked great - she never went through a stage when she was gangly or out of proportion or just not right. However, her sister's head has still have not filled out and she still has growth plates which suggest that there is still some filling out to take place and she is 2 years old. Her sister has been shown sparingly - to get her used to the ring - and she has won a time or two - but really there is no point in showing her seriously until her head fills out.
Good luck with your pup!