My experience so far is that it reacts differently on different growth.
I had two on which it worked right away. I did some liverspots (for which you probably are not old enough :)), and so far I did it about 3 times and now waiting.
Then I had one that looks like a skinny wart (also old age spot),
which is luckily on my leg and may be so far I did it 4 times and now waiting.
One mole is disappearing I did it twice and lost different areas and may be one more time it will be gone.