Google launched the new service “On-Demand Indexing” for webmasters who installed Google search on their site. The service allows the webmaster to independently “say” when to index his site. On the Site Search page, using the “Index now” button, the webmaster will be able to index and reindex the site pages. Previously, as you know, Google did it on its own “on schedule”.
As they say at Google, this service is designed so that the webmaster can “tell” the search engine that new content has appeared on its website or old content has changed. Indexed pages using the "Index now" button will be able to get into the issue only after 24 hours.