It is not sure how much time it will take for your site to come in top search engine ranking. SEO is ongoing process. If quality backlink is taken in proper category with quality link exchange than i am sure that result will come quickly.

Never know about this, check competition against keyword. Keyword having 100,000 searches or more take more time then keyword having 20,000 searches. Also look for competition some good traffic volume keywords have not high competition.