All upvote rewards in the first minute go almost completely to the author. With only at minute 30 all 100% of the upvote rewards are shared along the 75/25 maxim.
Given that more popular authors/whales usually benefit a voting trail they tend to get more of the share which otherwise would have been distributed 75/25 because many autovotes are before the 30th minute, those with more SP often even taking a higher penalty because their weight in the curation matrix is higher and they will still come out on top.
So if a whale self-votes within first two or three minutes, barely anything of their upvote is shared with the curators.