Usually, 7 business days. I submit my site to yahoo directory last month, what's difference I saw is I got more hits from yahoo SE. The submission price means you buy a link for $25 per month, for its authority, it is worth the money.
i don't even mess with directories their are so many of them and I think its going to be over ran soon and people are going to stop using them.
Check your referring sites, the editor from yahoo, comes from surf.yahoo.com, if your site is accepted you should get an email that day. When they visited my site they stayed exactly for one minute and visited 15 pages in that time so it´s not as if they comb your site with a fine tooth, any decent site should make it in. Also, I did ge to a PR4 about the same time, not sure if it had anything to do with that, the traffic has been sparse at best, and they submitted me to the wrong category. The one complaint I have is that after I mailed them with a change of category suggestion, they don´t even bother to write you back, they tell you to check back in 3 weeks to see if your site was changed. For 300 bucks they should at least have the courtesy of answering your mails.
I guess I would recommend it. I submitted one of my sites to the Yahoo directory and right away I saw a little traffic. Plus it is a great link from a trusted site. I would just pay for one year and then be done.
I mailed them already 2 times. No response. This is starting to piss me off. Might as well throw $300 in the trash.
Remember it´s 7 working days, saturday and sunday don´t count, so tomorrow would be the seventh day. My site go in on the seventh day.