Passives and "When Revealeds" and initiative counting is all very fuzzy for many of us Regular Joe AGoT players.

There was a situation today with Bay of Ice standing on the table when Attack from the Sea was revealed. Now, initiative is counted before "when revealeds" occur, such as would be on Attack from the Sea, but the timing chart seems to indicate that we do all of the 'framework events' before passives resolve. Thus, unless I misread the chart, Bay of Ice will be knelt by the time its effect will kick in.

Further, unless I misunderstand, since Bay of Ice's draw is preceded with 'then,' the entire preceding text must have been actually fulfilled. Thus, you could not draw from Bay of Ice on an Attack from the Sea turn.

Am I correct or have I run amiss somewhere?

Yes, the When Revealed passive happens before other passives (Bay of Ice), so the first part of the Bay of Ice effect will never happen succesfully, and thus the then part will neither.

That's one reason I'm always surprised to see people running Attack from the Sea in decks with Bay of Ice for it's high initiative…

Your conclusion is right. Attack from the Sea's "when revealed" effect is itself a passive, but the FAQ tells us "when revealed" effects must be resolved before other passives like Bay of Ice. So, unless Attack from the Sea's effect is cancelled (with Outwit, for example), by the time Bay of Ice resolves, it is already knelt, so no one will draw.