When you do SEO on your website you should start seeing results from the SEO within 3 to 6 months.
It also depends on how competitive your keywords are and even how many backlinks and how old your domain is.
The older the domain and website then the faster and easier you're likely to rank.
Sometimes it can take a year or more for your new content to reach the first page of google search so you do need patience when it comes to ranking a website and content in google search.
With yahoo and bing it's usually much easier to rank in their search engines and I've had some of my content rank the next day in yahoo and bing search and get traffic from them to the content the next day after posting the content and then it took a year to rank the same content in google search.
What people need to know and remember is that SEO and ranking in Google Search is a long term process and requires a lot of patience and work.
Remember too that google search ranks websites higher in search results the older it is and if it's constantly being updated with fresh content.
Google Search Loves fresh content so you have to constantly work on your blog or other website adding content at least once per week but you need to write quality content to get it to rank good in Google Search.
You can also speed up the process of google indexing your websites content by submitting the url to the new content to google search after publishing it.
Search Google for Submit URL to Google and a box will show up on google search where you can enter your contents url and then submit it to google for them to crawl and know about your content faster.
It doesn't mean it will rank faster but it does speed up the process of google indexing the content so it can rank in google search.