It can take anywhere between a few hours for PPC listings and many months for organic/natural SEO listings. with PPC (paid/sponsored listings) you can get your ads to feature on top as soon as a campaign is setup and ready, you will then be able to enjoy targeted traffic within 20 minutes. with SEO organic/natural campaign it is depending on many aspects and mostly on the length that your domain and site are online, what kind of Page rank your site enjoys and the amount of links it pulls in from other relevant sites. all these can take a few weeks for an established site and 3-10 months for a new site.