It depends. When the piece is published in a journal hosted by a large publisher (Wiley, Elsevier, Springer, Taylor & Francis, Sage etc.) it normally only takes a few days in my experience. Google Scholar seems to scrape these pages very regularly and efficiently. However, if it's posted on an institutional repository, for a new journal without a big publisher backing it up, on another hosting site or if it is a different publication form from a journal article, it might take much longer, that's true.   

I find that Google Scholar still does a much better job than most other such services. Check out the attached publication on the topic!

Working Paper The counting house, measuring those who count: Presence of B...

Yes, yes, too long, I'm afraid too.

I have to agree with my colleagues. For example, I have realised that my article was cited few months ago, this article is in RG data base, but citation does not appear in both Google Scholar and ResearchGate. 

I do receive Google Scholar alerts, but most of them are wrong.

Google Scholar presents all the benefits and drawbacks of the WWW. So, your citations are computed and updated automatically as Google Scholar finds new citations to your work on the web.

P.S.: Google Scholar generally reflects the state of the web as it is currently visible to their search robots and to the majority of users. If some of the citations to your article are not included, chances are that the citing articles are not accessible to search robots or are formatted in ways that make it difficult for their indexing algorithms to identify their bibliographic data or references.To fix this, you'll need to identify the specific citing articles with indexing problems and work with the publisher of these articles to make the necessary changes (see attached link on inclusion guidelines for details). For most publishers, it usually takes 6-9 months for the changes to be reflected in Google Scholar.

http://citationsmining.blogspot.com/2013/04/google-scholar-citations-help.html

It depends. When the piece is published in a journal hosted by a large publisher (Wiley, Elsevier, Springer, Taylor & Francis, Sage etc.) it normally only takes a few days in my experience. Google Scholar seems to scrape these pages very regularly and efficiently. However, if it's posted on an institutional repository, for a new journal without a big publisher backing it up, on another hosting site or if it is a different publication form from a journal article, it might take much longer, that's true.   

I find that Google Scholar still does a much better job than most other such services. Check out the attached publication on the topic!

Working Paper The counting house, measuring those who count: Presence of B...

Additionally, I should say my total citation in Google Scholar is higher than my total RG citations. So I guess Google Scholar is regularly updated. 

Given that the various scientific databases have their own characteristics, the attached article tries to compare the utility of the current most popular sources of scientific information such as PubMed, Scopus, Web of Science, and Google Scholar, in retrieval of information on a specific subject and in up-to-date citation analysis.

http://www.fasebj.org/content/22/2/338.full

Dear @Ruchi, let me bring some relevant threads with good answers,as well as some blogs about the issue.

Dear @Kristoph, thanks for publication. I have downloaded it.

https://smallpondscience.com/2015/07/27/im-going-to-stop-ignoring-researchgate/

https://www.researchgate.net/post/Google_scholar_for_systematic_reviews_what_limit_on_search_returns

https://www.researchgate.net/post/Does_anybody_know_how_we_can_add_the_missing_citations_to_our_profile_in_Google_Scholar

https://www.researchgate.net/post/Importing_publications_from_google_scholar

https://www.researchgate.net/post/How_can_I_add_or_import_my_google_scholar_citations_to_Research_Gate

ORCID is a further useful place for make your work public. This allows to get automatic updates from Scopus, google scholar, web of science et al to a list that you can update also yourself.

It might be a good idea for RG to allow for a an interface to ORCID as well.

See also UC Library » Library Guides » Library Guides »Research Impact Factors (link below).

http://canberra.libguides.com/content.php?pid=157360&sid=4381638

https://orcid.org/

PS: Recently, I learned that arXiv.org also has an interface to ORCID, and plan to use the ORCID for identification of arXiv authors.....

It only takes several days for my recent publication in Applied Physics Letter.

I noticed that GS has not updated my citations in over a month now, which is unusual.... I am wondering if there is something wrong with the system or whether in fact Might not have gotten any in the past month (yet RG, which is typically late compared to GS) is showing new citations and they don't appear in GS.....

It can take up to a week before an arXiv upload shows up. I am currently on the 5th day of waiting for a recent arXiv preprint to show up. I would be curious to hear what others experience is.

Curious... my review article "Deep learning for molecular generation and optimization-a review of the state of the art" appeared on Google Scholar over two months ago on my Scholar page and in search results, but the it doesn't appear in "works that cite this" lists for the articles we cited. This is strange because I'm using the exact same citation format as other arxiv preprints that have showed up. The only thing I can think of is maybe Google doesn't include arxiv in citation counts anymore, but I can't find any info on that and it seems they still do generally. Anyone know about this?