new kitten hasnt eaten

Hi - I'm a little bit of a hypochondriac so I may be over reacting but I'm nervous nonetheless.  We picked up a 10 week old kitten from the local Animal Shelter at about 4:30PM or so --- its now about 12:20AM and she hasn't eaten or used the litter box at all.  She drinks water shes TOTALLY playful and loving and energetic; and she lapped up a tiny bit of milk we put out on a plate for her, but she isnt going for the food at all.   We bought Blue Buffalo brand for kittens.  Should I be concerned?

Do you know what the shelter were feeding her? It's best to slowly change to a new diet if you can.

It's not unusual for kittens to stop eating at first when going to a new home. 

It's very common for kitties to not eat/use the box for many hours in their new home.  Most likely she'll eat overnight when it's dark and quiet.  Please don't give her milk as most kitties are lactose intolerant and will end up either throwing up or with diarrhea.  You can give her a bit of KMR (kitten milk replacer) in her food if you think she needs some extra nutrition.  Also, as the previous poster mentioned, give her what they were feeding her at the shelter for a few weeks until she's settled in your home, then work on gradually changing over the food.