Hedgies are typically considered adults around 6 months, though they'll still grow and fill out a bit more after that. What's her body shape like? If she's a normal teardrop shape, or seems like she might be getting a big pudgy, I would go ahead and switch her to an adult food now, with less fat. If she's a runner (sides go straight back like | |), she may always need a higher fat food, to help keep her from losing weight.
Besides the debate of kitten or adult...I would suggest switching her food anyway - Purina kitten chow is not really good quality food at all. A good quality cat food doesn't have any corn in it, has a named meat or meat meal for the first ingredient, a protein content of 28-35%, and fat content (usually) between 10-15% (usually 15-20% for runners). Some of the brands that are popular on here include Natural Balance, Solid Gold, Chicken Soup for the Cat Lover's Soul, and Blue Buffalo. They're a bit more expensive, but they're much healthier for your hedgehog, and hedgehogs don't eat much anyway - you're much more likely to have to throw away the food from staleness before your hedgehog finishes the bag (though you can extend the life by freezing it).
It's also a good idea to use two or more foods in a mix. This helps make sure you're catching all of the nutrients (since we don't know exactly what a hedgehog needs), and also as a safeguard in case a food becomes unavailable, since hedgies can be very picky and may go on a food strike if their only food isn't available and they're suddenly switched to something different.
She looks to be tear dropped shaped. She is right at 311 grams now. Runs at night but hard to tell how much. I will look at switching her to a better food. I just went with what the breeder said to feed her. Thanks for the help!