Marketing for a restaurant should begin early in the process before the website is even complete, and months before the actual grand opening. You want people to be aware, eager even, anxiously awaiting your soft and grand openings.
Marketing has several stages, from social media promotion to advertising, to search engine optimization of your website.
Optimization takes months to get traction, and these efforts are essential for people to find your website in search; to get your site listed high in search rankings so people find you.
Optimization also requires off-site activities, including, but not limited to getting listed in all the location-based directories. So it is important to get your branding complete, set up your social media pages and other branded pages accordingly, and, have a newsletter set up to build a mailing list for future promotions.