When you are ready to deal with her getting up early in the morning and possibly some during the night. Once they can get up by themselves....they will. Mainly becuase it is a new adventure.
Also if they start climbing out of the crib, it is safer to put them in a bed.
We put our oldest in a low bunk bed with side rail when he was 13 months old because his sister was born. We did not have a second crib. It worked just fine for us because he was a snuggle bug and just came to bed with me ta 6 when he woke up.
Dd woke up later than him so I was already up.
Third kid pretty much same story. But they key, I think is...that I got up when my kids were up no matter what. If I was tired then I tried to keep things subdued but I did not expect them to stay in their room and be good while I slept.
So basically move to the big bed when you are ready. It does not hurt to do it at this age or wait till 18-20 months like I did with the others. Some people even make the big bed their 2 yr birthday thing.
Good luck