Depends on several factors like website AGE, Number of backlinks, Content and Niche. Unless someone does a thorough research on your page 1 competitors,they will only give you a general assumptions! Most of the above suggestions do work but after you do research on your competitors, you will narrow down to the factors to know what it will take you to rank on top for your main keywords!
Usually it takes 3-6 months to rank for a low to mid competitive keyword to rank considering you are on point with Offpage & OnPage.
Good Luck!