If you haven’t tossed the labels yet, don’t!
Place them on the outside of the stamp case, underneath the thin vinyl cover that covers the stamp case.
If you open up the stamp case and set it face down on a table, the thin vinyl cover will open up and you can sneak those stickers onto the back of the stamp case. They will stay there once you close the stamp case.
Then put your stamps inside, matching the stamps to the placement of the stickers on the back.
Having the stickers to look at is a great help. They don’t need to be on the back of the stamp and having the sticker handy to look at before you stamp is really all that is needed.
Hope you find a solution that works for you.