I write posts ahead of time. I wrote this one days ago. later, I'll come back and touch it up and then post it.
Then I'll realise I forgot to update the timestamp, so it's listed as being posted days ago. So I'll go edit it to reflect the current date and time and repost.
Personally, I think the 'Post time and date' field (that's what the editor calls it: 'Post time and date') should automatically update to the time I posted the thing, not when I typed the first letter! At least change it to the last time I edited/saved it.
(Truth is, I won't forget to fix the timestamp on this post, because I'm going to append 'FIX THE TIMESTAMP' to the title so I'll remember. But I usually don't bother doing that, and I really shouldn't have to. Blogger needs to get on the ball.