Is bookmarking is effective? How many days it will take to index?

Yes,
Social Bookmarking is useful for increase Page Rank and Keywords ranking because SB submission is fast approved. If you do social bookmarking in Dofollow sites then they gives you the backlinks. And it is very helpful to increase traffic on your site.

Yes bookmarking is still effective, indexing totally depends on the website you link. If its a high traffic generating website then it will get index within a days time.

Social book marking is always effective and it will be. It is the best way to get indexed in the search engine quickly. And it is not any fix time to get indexed. Some time you will indexed in just 1 day, some time it may take a week or even a month.

Social Bookmarking is effective to get more visitors on site and also to cache & index it fast.

Yes, Bookmarking is helpful to increase traffic on a website.

Book marking is now more popular after finished directories. Its a best way of promote meta keywords & meta descriptions.

yes. It is effective and it does improve keyword rankings.

Social bookmarking can be effective if you will use high page rank do-follow bookmarking website.You should also care about use of anchor text you use.You should use a variety of keyword for a targeted page.