How long does it take for a search engine to update the content of a web page?
It is impossible to answer this question precisely.
The answer depends on several factors and anyway, we could only get an estimate.
Being more visited by the search engines than the others, web pages with a strong PageRank are refreshed more frequently.
Robots will also be more reactive on a page that is identified as regularly updated.
If a page doesn’t correspond to any of these cases, then the solution would be get new links that point to it.
Getting those links will prompt the robotos to browse again (or for the first time) the targeted web page.
It is perfectly possible to see hundreds of indexed pages only 24 hours after a website launch, as well as to receive engine traffic.