It's perfectly normal for a budgie not to use a cuttlebone right away. In fact, they may not use it for months on end!
Cuttlebones are great sources of calcium, so a budgie will only eat from it when their body is depleted of calcium. Although they don't use it all the time, it's still important to keep it in their cage since you don't know when their bodies will require more calcium
A variety of perches and lots of chew toys can help to keep her beak and nails trimmed to the proper length while she's not chewing on the cuttlebone.