There is no set answer to how long it takes before you start seeing organic improvements from SEO efforts, as it depends greatly on where you are today, what SEO work has been done, and what your competition levels are like.

In general, most websites on page 2 can be brought to the first page within 3 months. As for a new website, you’re looking closer to 6+ months to get good first page rankings on competitive keywords.

During that time your leads and traffic will increase gradually and regularly, but the big wins are once you hit the top half of the first page.