It varies between engines. Altavista and Infoseek/go usually have your site listed within 48 hours or so. Places like hotbot take around 2 weeks, other vary from time to time. Generally you will be listed within 4 weeks of submission.
Dont forget though, if you used a auto-submitter then you may not get listed at all. Alot of the major search engines now have these programs blocked off and do not list sites submitted using some of these programs.
Always submit your site manually to the top 20 or so engines. Then auto-submit to everything else.