Curation rewards are not on a first come first serve basis. There is a penalty for voting anytime anytime before 30 minutes a post is made. If that's the case, all or some of the curation rewards go to the author. Curating at 30 minutes or anytime after that means 100% curation reward to the curator.

Here are some details
Voting above 30 minutes into the post, the author gets 0% whilst the curator gets 100%.
Voting above 20 minutes into the post, the author gets 54% whilst the curator gets 44%.
Voting above 10 minutes into the post, the author gets 89% whilst the curator gets 11%.
Voting above 5 minutes into the post, the author gets 97.2% whilst the curator gets 2.8%.
Voting above 3 minutes into the post, the author gets 99% whilst the curator gets 1%.

Rewards are paid out when the first payount time reaches.