Her phone would need to be signed in with your ID in order to restore to her backup (since it's in your account). Go ahead and set it up with your ID. Then you can migrate her phone to her own account by going to Settings>iCloud, tapping Delete Account, choosing Keep on My iPhone when prompted, then sign back in with her new ID to create her new iCloud account, turn on her iCloud data syncing and choose Merge to upload the data to her new account. (Deleting the account only deletes it from her phone, not from iCloud. Your phone won't be effected by this.)
If she wants to keep photo stream photos from your account on her phone, she will need to save them to her camera roll prior to deleting the account (by tapping Edit, tapping the photos, tap Share, tap Save to Camera Roll). Also, if she wants to keep any notes on her phone from your account, she will need to email them to herself before deleting the account so she can recreate them in the new account.
If she needs to change the ID for iMessage to her own ID, go to Settings>Messages>Send & Receive, tap the ID, sign out, then sign back in with her ID. Do the same thing in Settings>FaceTime. If she wants to use her own ID for purchasing, do the same thing in Settings>iTunes & App Stores.