By submitting your sitemap, google crawlers "crawl" your site much faster. Again, normally it would take around 2 weeks for your site to get indexed. By submitting your site's sitemap, Google crawls it and idexes your site faster.

...the main purpose of a Sitemap is to make the job of the search spiders easier and more efficient, thus encouraging a faster crawl rate in the future. So while it has great long term effects, it’s not necessarily going to be the heavy hitter in getting you indexed quick.