That entirely depends on the strength of his competition and a few other factors, f.e. how fast his site is loading, if he has the exact match domain etc. If you're trying to rank for a term that almost nobody optimized for, you'll rank in the top 10 in even less than a month without any problems or sweat.
lots of things to consider indeed and time... even I don't want to do seo cause its time consuming and so many things to consider but i guess we don't have other option
You're right, SEO is time consuming and you need to learn quite a bit to understand what to do in order to get your site to climb up the ranks. But you do have another option: Outsource it to people that know already what to do to get a site to rank highly.
You can even get top in just 15 days. But it depends upon competition, and the number of backlinks, you are getting.
In order to the top 10 place in goggle first you have to select your targeted keywords you want to rank for.Then you have to use different types of off-site SEO optimization job to get your site in top 10 for those keywords.
Go through out all strategies simultaneously. You should create backlinks with good quality, not with quantity for a proper ranking in SERPs.
Firstly Emphasizing on Backlinks.Good backlinks helps to bring your site in top page rank on Google.For to have good backlinks you should keep comments and posting on Forum.Article Writing is also effective. Focus on the keyword research which is more important. Try to gather more traffic by advertising or in other way to make it a trustable and famous site on the eye of Google. finally keep patience.Think positive thus your luck will also be positive to you. All The Best.
Signature links, blog commenting, link exchange (try 3 or 4 way) and many more. You can also buy links but Google hates this.