This is a tricky question to answer – whilst it’s true that most SEO effort will take time to show results (several months, in some cases), there are other changes that can have a much quicker impact. Ultimately it really depends on the work that is being carried out – I’ve worked with clients that have had key pages “hidden” from Google, so resolving that was an instant fix which delivered traffic nearly overnight. Other content based improvements can take months for Google to crawl, re-evaluate and re-index. So in true SEO fashion, the answer here is “it depends”. I like to think most of my clients start to see results from the 2nd or 3rd month.