If you vote right away, you get 0 curation rewards. If you vote at 30 minutes, you get the most curation rewards potential for your SP weight applied on voting. People with more SP get more curation rewards than those with less, as they increase the potential payout and therefore get more in return.
You want to vote early in case someone with more SP, and more people voting, start to vote, so you can get more curation rewards.
Anyone can vote after anyone else but you get less reward potential from curating. Anyone that votes before gets more curation potential that those who vote after, according to their SP weight applied. A whale will always get most of the curation rewards no matter when they vote, because they are a whale who is giving more potential rewards to the post.
It's all about SP you have applied and the voting weight applied, vote power applied, and also the time you vote within 30 minutes, and the people who vote after you. A whale voting after you will give you more curation rewards than if you voted after them.
good info! thanks for explaining that.