You mustn't overthink this one. Curation rewards happen when you vote.
A post that is on the platform makes $10 for example. I wont include the lost vote or burn vote as that would just over complicate things. The author receives roughly 75% so in this case is $7.50. The rest of the rewards which are roughly 25% will be $2.50 for all the curators.
Percentages vary on what time you voted on a post. They say the ideal time is 15 minutes but I vote on 13 minutes before the masses arrive. I have noticed I earn more just before than on 15 minutes when everyone else votes.
I wouldn't worry too much with curation because it is only a small percentage of your rewards. Use your vote on posts and comment. You will earn way more this way as that is how I grew. A worthless vote where you will be lucky to get little or no curation could attract 5 c or 10 c or maybe more back from a user, When your account is bigger then you can play around with curation.
Curation Rewards are a bit complicated to understand. They are a system that wants to reward the ones who discover good posts, that get upvoted by other steem users later on. And that's also how they work mathematically, but first I will make a small explanation about what rshares are. Rshares are the blockchain intern values of votes, and they are pretty big. The vote I gave on your post, has 9781236793 rshares. That is a freaking lot. Now lets get to the curation rewards!
(I will ignore the 15 minute curation penalty for this explanation)
When a post gets paid out, 25% of its rewards go to the voters of said post. These are the big pool for the curation rewards. Now, there is a formula for the curation rewards of one user:
curation weight of a vote=
√(rshares after the vote) - √(rshare before the vote)
This means for your curation weight, only the votes before yours get considered. Now, you get a part of the curation pool as big as the part of the sum of all curation weights your vote is. That means if your curation weight is half the sum of all curation weights, you receive half of the curation rewards and so on.
Because this formula is using square roots, that means that you get more reward for your upvote (in relation of course) if you give smaller votes. That's why curation snipers like @cheneats, who try to get as many curation rewards as possible, always upvote with small upvotes.
I hope this explains it enough. If not, please ask what you did not understand, and I'll help you get it ;-)
On Steemit, you can earn rewards through blogging / commenting and by voting too! When you upvote another person’s post, you receive a fraction of the total value of that post in the form of STEEM. These bits of STEEM are called “curation rewards”. In this post, we’ll talk about best practices for earning these rewards and strategies for maximizing your impact.