How Steemit curation upvote works in detail

1- Every post's payout is divided in fix share ratio of 75% and 25% while 25% goes to curators (upvoters).

2- Upvoting your own posts and comments is generally considered not good but even if you do that timing does not matter in this case. You can chose to upvote yourself close to post creation time or payout time, your reward will remain the same.

3- When you upvote other's post - timing is very crucial specially first 30 minutes. If you upvote after 30 minutes then curator gets more reward but if you get closer to post creation time then author will get more reward share.

4- Voting power always plays great role in curation. You can decide to control your voting percentage for every upvote but you get to chose that only when you have 500SP. So thing is if you are at 100% of your voting power and suppose your vote's worth is 1$ and you decide to upvote with only 50% vote strength then your curation will contribute only 0.50$. Similarly, if your voting power is currently at 50% and you decide to upvote with vote strength of 50% then your contribution would be 0.25$.

• What are curation rewards?
  

A reward you receive when you vote on a post. At least 50% of the rewards always go to the author, the other 50% is divided between the author, the curators and the commenters. Curation rewards are paid out 100% in STEEM POWER, which increases the power of your up-votes, so you help the content creators and yourself!
It took me some time to fully understand the whole dynamics of Steemit curation. Its a little complicated for beginners & minnows. So i decided to share it with my fellow Steemians.

• If you vote immediately after a post is submitted: The voter gets almost zero, the author gets nearly 100%.

• If you vote 15 minutes after a post has been submitted: The voter gets 50% of the curation reward, and the author gets the other 50%.

• If you vote 30 minutes (or later) after a post is submitted: The voter gets 100% of the curation reward.

The time-reward relationship is linear. The reward is progressively changing throughout that first 30 minutes. So the 15 minute mark is just an example; there is no special milestone occurring at 15 minutes. The only real milestone is at 30 minutes, when the voter hits the 100% curation payout. Until then, the author’s portion of the reward is declining and the voter’s portion of the reward is increasing, the longer you wait to upvote the post.

That means that you could jump in at any point with a vote, whether it’s at the 2 minute or 10 minute or 18 minute or 23 minute or 29:59 minute mark, or at any other point, and you would land on a point where your split with the author would be very predictable.