Timeframe to notice changes

Hello all,

I am just getting more into the real aspects of SEO and doing some reading.

This may be a basic or hard to answer question, but 'normally' how long does it take to see any change in the ranking of a web site?

I am redeveloping a web site for a rental agency. They are currently not showing up in my search using the Advanced Web Ranking program to find the site. The changes are just about ready to be launched and implemented, but I wanted to know what I should expect.

Will it take 1 month, 3 , 6.etc... to notice anything?

Thanks.
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