Hi there, it wouldn't be unusual for a 1-0 to happen around now, if not before, but there is also often a sleep regression around birthdays. So, if you find that this goes on for more than a couple of weeks then it probably is the start of the 1-0, but you could choose to see if it passes in time if you like first.
Why not have a read of this very helpful link:
The 1-0 transition...Advice and Tips to help you through.As you do go into the 1-0 you do need to reduce sleep from somewhere in order to prevent resistance and NWs. How you do that does depend on how your LO copes (and it is a slow and long process for some). My DD preferred to shorten nights a keep a full length nap that got later and later over time, eventually ending up with nights of approx 10 hours only. Around this time we then dropped the nap and her night sleep went straight back up to 12 hours each night and she was really ready for sleep by that point.
You might find as mentioned in the link that she manages better with an earlier morning, or a capped nap.
What do you feel might suit her best?
N x