Some marketing avenues produce very quick results and it doesn’t take long to see if it has worked for example, email marketing or pay per click campaigns, which can attract visitors to your site immediately after the adverts have gone live. You may send out an email flyer one day and within a few days you will be able to see how many people have opened it, clicked through and then purchased something off your site. This will allow you to establish a cost per acquisition and see if it is a worthwhile marketing tool for you to use again in the future.
Other sorts of marketing, such as Search Engine Optimisation, may take a little longer. You may need to give it six to twelve months to really start to see a benefit from it and even then this benefit may only be small to start with. With SEO you can often improve individual key words a lot quicker by adding new pages that have relevant text to the keyword or phrase. These may only take a week or so to start working. SEO needs to be built upon and as your competition may also be marketing their business, if you stop you may quickly fall behind them losing you valuable business.