yea in first 30 min author gets maximum reward....Thats 100% true but you also get maximum reward lemme explain with an example earlier votes get maximum curation reward but it also reduces the value of total reward pool if your vote is worth alot like 10$ andyou vote on first min only then almost 99% of your 10$ vote will go into author reward that is almost 9.9 for autor and 0.1 for curator but if overall earning of the post is now 100$ frm whic total 20$ is going into curation then as your vote was earliest you will receive maximum curation reward like you will receive almost 18-19steempower.......but if the post overall make only 12$ after your 10$ vote then total curation will be only 0.1-0.5$ and what you will receive will also be low