How long will it take my canine to fall into its natural place after having a URA fitted?

My orthodontist has said I can get a URA fitted instead of a fixed brace. I'm just ordering how long my canine will take to come down? As you can see on my photo I still have my baby tooth below it which has caused the second tooth to grow wrong. My orthodontist said it should take long and that it's in a good position for it to just fall back into place but after how long? Thanks for your help.

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