As a start point,make up many (and there are) words, using the letters A,B,C,D,E,F and G. E.g. DAD, CABBAGE etc. Then encourage her to play the words on the keys. Each will make its own tune, and for now it matters not which octave each letter (or each word ) is played in.
DO NOT put the letter names on the keys ! They are already in a quite easily understood pattern, so it's a waste of time. A D note, for example, will always be between the TWO black notes, so E is to their right, and C is to their left. There's 3 sorted very easily !
Get her to play a word in 3 or 4 different places, same pattern, and she will soon find her way round the keys.
Incidentally, reading the little black dots on the music has no DIRECT correlation to the black and white keys. So don't try to put this into the equation till the keyboard itself is well known.People will disagree with this statement, but I believe it's true. There is no logic in the fact that bottom line, treble clef is an E above middle C. Convention puts it there, so initially she would be trying to learn TWO different skills. Why bother ?
Even when she IS playing from music, don't worry too much if she plays in tne 'wrong' octave. The tunes will still sound good, and it's sometimes fun to move a tune about.