There is no publicly known set schedule when Google crawlers visit your site. You just have to make sure your site follows best practices. Also, certain web analytic tools allow you to detect crawler/spider activity.
Do you really want your site to be on the 5th page of SERP for Google? REsearch shows that the majority of searchers only view 2-3 pages max. Thus, it is very important to optimize your site to appear on the first page by following all the best practices.
Getting to the first 5 pages is not to difficult, getting on the first page takes time and research. update your content and play with long tail phrases. dont forget, if you are selling something on your site, use a keyword like "get" and "buy" this means the person searching for a specific item actually want to purchase the item :P
In my own experiences, targeting right keywords would be the most important step if you expect a successful SEO campaign. Generally speaking, title tags and backlinks with your targeted keywords would be 2 top issues for ranking purpose. Also, Bookmarking your sites on some hot sites like stumbleupon and submitting your articles to those hot article directories would usually make your links on Google SERP for your keywords promptly, IMO.
First Start your SEO activities from article submission by targeting the keywords you want to have top position, then make a list of forums related to that keywords and also gather list about high PR blogs related to same keywords. Make signature on forums and post on relevant pages. Also post on blogs but not too many of them, try to make profile links on high PR sites forums, For quick crawling try to add new content and get some good PR links
No one actually knows when Google updates. But before that time comes, make sure that have your quality content together with creating quality of inbound links to make sure that you get to your desired ranking.
You are talking about achieving results on Google and the only way would be to use and follow SEO guidelines and methods. For example, nowadays links are playing very big roles over the net, shaping a lot of great and profitable businesses and based on the keyterms you have chosen and how competitive they are, you will need to add some links to your website and then be patient for some time because SEO is a long term process.