While results with some Search Engines can appear within 2 weeks, the time frame for respectable results is 2-3 months from the initial indexing. Although "pay for positioning" expedites the process, it requires separate fees paid directly to the search engines and directories.
0-1 week Inktomi, and less recognized search engines
2-4 weeks Altavista, Infoseek, Google
3-5 weeks Excite, HotBot, Lycos, Webcrawler, Northern Light
6-8 weeks Yahoo
Please note: The above results are subject to change.