Stickers

ravandenheuvel wrote: How long should I keep the sticker symbols on the keys? At some point it seems like it will be more of a crutch than a help.

It is like a band-aid. If not needed, time to remove. I would suggest to replace the stickers with piano key guides for more gradual transition.
The numbers on the time bar should not be increased drastically (remember: healthy is when amount on the right is less of amount of correct notes)
If one day key guides will become also over stimulating visually, remove those too.

My daughter is 6 and this is her 4th month of learning this system. Thanks!

Seems like perfect development to me. Wish to see at least her hands playing to give more feedback.