I just check my keywords---dell latitude d620 battery, now it in google page 28, and it has firerce competition. I want to rank it in the google first page? How long it will need?
Exact time depends on the effort you make to do so. You will need strong amount of backlinks with the same keyword from similar sites. And also your content on that page should be informative as compared to your competitors, you may do keyword research and improve content to make it more relevant to that keyword.
i agree with basickno, the key to getting your page ranked on page 1 of google is to build back links and lots of them. There are many ways to build backlinks, but I find article marketing most effective. The time taken will also depend on your competition if they continue to build their sites to stay on page 1, you are going to have to put in more effort.