This question is similar to the “How much does SEO cost” question. The amount of time required to rank well for one website versus another can vary significantly. But, the general rule of thumb is to expect to start seeing good results in about three to six months of SEO. Recently we’ve seen some thought leaders in the industry say four to six months. However, this is definitely a general rule of thumb and the exact amount of time needed for you can be different.
Going back to the example shared in the question about SEO costs, if you’re an attorney, it may take a lot longer than six months to rank well on search engines. Then again, if you sell VHS cassette tapes, it may take a lot less than three months to rank well.
Also, consider your budget. If you’re spending significantly more/less than what most companies spend, that can also impact the amount of time required to rank well on Google. We’ve had clients rank amazingly well in as little as one month. We’ve had other clients in competitive industries focus on a small and steady climb, and actually spend years building up their SEO. The amount of time it will take you depends on your unique and specific situation. But, as a general rule, expect to start seeing good results in around three to six months, assuming your situation is “normal.”