6 to 12 months for the natural dissipation of the smell depending on fresh air circulation. I've heard of people using activated charcoal in dishes set about closets and such when they've purchased a home that had the smell lingering from a previous owner's use of the balls. It still takes time tho.
Experience is what you get when you don't get what you want.
"We'll be friends until we're old and senile,....then we'll be new friends."