What is the effective way to start the seo process for a e-commerce website so that we can get top keyword rankings for the no. of kwds ? And how many weeks it requires to get the top rankings of the keywords ?
All depends on your keywords, what is the competition, do you have short keywords (1-2 words) or do you have sentences. Usually is taking 2 weeks to see the first movements but all depends on their importance. Take a look on Google Keywords Tool from your AdWords account and there you may see the importance of each keyword that you wanted to be ranked.
Smartly choose long tail keywords for your website & for inner pages. Write good catchy title tags, meta description. Install google analytic, webmaster tool, submit sitemap. If you do Good On Page Then that will give really good traffic.
Make you website SEO optimized through On page SEO .... Do some off page SEO as well and then put your portal ads on Google Adwords.....