I can guarantee to in increase website traffic, Improvement of SEO health and website ranking and genuine leads to your website.
If you are referring task to website SEO, then Complete website SEO would require at least 2-3 weeks to complete.
Increasing the traffic will require around 2-3 months. As I will complete the SEO that will include fixing any errors, optimizing the content of the website and straightening out the structure. After only this the website can start to gain its position on search engines.