Now trying to vote up, get message that I voted 16 hours ago and it's locked.
Should I wait 24 hours?
PS. 24 hours passed, but it's still locked.
When I'll be able to correct my mistake?
Your vote is locked after a certain time(5 minutes). You cannot edit your vote unless the post you voted on is edited.
For further reference see this answer in meta.stackexchange which says,
In general, once you have voted, you cannot change your vote. There are two exceptions.
- Exception one: you may change your vote a practically unlimited number of times within a five minutes window from the first vote you
cast on that post. Note that after changing your vote ~60 times, it
will also be locked in.
- Exception two: you may change your vote after every time the post is edited. A new window starts with the first vote you cast after each edit.
Also on a further note please use meta.stackexchange.com for such questions about Stack Exchange rules, etc...