I think these are the current rules:

https://steemit.com/steem/@steemitblog/steem-0-8-0-released

"Starting *TODAY all curation rewards earned by voting in the first 30 minutes after a post is made will be shared with the author. If you vote immediately after a post is made, then 99.94% of the curation reward will go to the author. If you vote after 15 minutes, then 50% will go to the author. Any votes made 30 minutes or later 100% will go to the curator. This only applies to the curation rewards. The author still gets at least 50% of the total rewards."

"After the first payout on a post is made it is possible for additional payouts to be made if more votes come in later. These “late votes” will no longer qualify for curation rewards."