Are you currently enjoying cosleeping? If not, go ahead and change it. If so, keep doing it! You know your needs AND your child's needs the best - if you decide to transition her, just remain flexible and aware as always, and you'll know whether she's ready (she'll tell you, loud and clear).
We are currently cosleeping w/ our 9 month old, and our 3.5 yr old coslept with us until 2 or 2.5 yrs. We just made sure to do a gradual transition. If my memory is correct, she was in our bed, then sometime after 12 mos old, we put a smaller bed right next to our bed where she slept for a while. She did do naps in her crib, or if I napped w/ her we did the bed. At some point we moved that secondary bed to her own room, and one of us snuggled her to sleep before joining the other parent back in the parents' bedroom. We had an open door policy where she could come in if she needed, and some days she would climb in for an early morning snuggle around 5am, which was fine for us! We enjoyed her company. The whole thing was gentle, gradual, and worked well for all of us - if someone felt like something wasn't working, we'd tweak it as needed. Now at 3.5 yrs, we do a bedtime routine, finish with a book and hugs/kisses, then lights out and maybe a 5 minute snuggle, but it's pretty low maintenance at this point. (So please don't worry about having a 12 yr old in your bed - that's just ridiculous - seriously!)
At six months old, I'm sure the transition would look a bit different, but just remember that there are *sooo* many big changes coming up physically and developmentally that might make for a more challenging transition (teething, walking, talking, more mature small and large motor skills, etc.) than if you waited another 12 months. HOWEVER, if *you* have reached your limit and are unhappy cosleeping, definitely make some changes. A good, calm, predictable bedtime routine will help as well as making her own room/sleep environment a really inviting, soothing, comfortable space.
Best of luck to you guys in finding the right balance/sleeping arrangements!