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the way it's established is
0-15mins = 99.94% goes to poster, 0.6% to curators
15- 30 = 50% - 50% ** 15mins mark isn't a set in stone threshold, the only real one is the 30mins mark.
30+ = 100% to curators
This is only valid for Curation rewards, the author still receives 50% or more of the total rewards.

Source = https://steemit.com/steem/@steemship/how-to-vote-smart-and-profit-from-steemit-s-new-curation-rewards

We might think that waiting 30mins before upvoting / commenting would be the smart thing to do, but truth is, waiting that long opens the door to not being among the first to upvote / comment, so by the time you do so, others will have jumped in before you, and this dilutes the rewards.

You've mis-understood what @steemship was saying,

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.

(own emphasis added)

If you vote after 14 minutes, you'll forfeit something like 53% of Rewards due to you, not 99.4%

Read this post for a full picture of how it works/ when and why the rules works that way:
https://steemit.com/steem/@steemitblog/latest-curation-reward-solution

Our solution is to offer a reverse auction for curation rewards on votes cast within the first 30 minutes. The price starts out at 100% of your curation reward and falls toward 0% over 30 minutes using the curve (1-t2). The longer a bot waits to vote, the lower the fee will be. However, if someone else chooses to vote before you it would lower your potential absolute reward.

Appologies, I indeed misunderstood , thanks for the precision and the link :)