How long do you think it takes for SEO to take effect on a website?

I've been using my website for several weeks i know it is a recently published website although I had been working on it for a while and now I'm having visits but I wonder if this is all SEO can do, how long do you think SEO can take to consolidate?

I've heard several times that it takes months but I wanted to know your opinion anyway! And if you have any advice that really works to position a website, comment on it!

If you have a personal website or blog already published, you can talk about your experience, and all the help is very useful!