This is incorrect.
Almost 100% of curation rewards due to you will go to Author if you vote almost immediately after they post. If you vote on 15 mins 50% will go to the Author. If you vote on 10 mins 66% will go to the Author. As a Curator you need to weigh up whether you want to lose out to the author or to other votes. A lot will depend on when you think others (particularly those with more SP) are likely to jump in and vote.
You have it backwards, its after 15 min it goes to 50% . 10 min would still be 99.8% of your rewards goes to Author.