IIRC they moved it up to a Thursday release (instead of a Tuesday release) in order to avoid more leaks and accommodate all the pre-orders. The downside, of course, is that they only 5 days (instead of 7) to count for the charts that week, though it didn't matter/makes the initial sales numbers/records even more staggering when you realize its really for 5 days and not 7. Here in the US, it was released on the following Tuesday, per the normal release schedules at the time.

When they shot the cover, they did it with a blank calendar that was filled in digitally later once the release date was established.

Yes, but I believe the original plan was to have one world-wide release date. When they shot it they didn't know what the dates were/didn't want people seeing the release date, so it was blank and added in later. I'm sure it made it easier to move up the UK release date.

Hahahah leaks. In 1997 the internet blew. How were these leaks getting passed around so quickly? Just cassettes? Seems like a lot of work for low payoff.

Journalists issued with a cassette of Be Here Now had to sign an absurd contract stating that they wouldn’t talk about the album while in bed with their partner. Ignition brought lawsuits against nascent fansites that carried any trace of copyrighted material. They called the police on three local radio stations that broke the embargo for lead single “D’You Know What I Mean?”, and pulled a raft of exclusive tracks from the BBC Radio 1 Evening Session after it was deemed that DJ Steve Lamacq hadn’t layered enough jingles over the songs to deter home-tapers. Even label staff were forbidden to enter the office at certain hours, lest they overhear the album, and at one point, Creation got a specialist in to check whether their phones had been tapped by Murdoch rag The Sun. It’s almost as if there were stratospheric amounts of cocaine involved at every level of the operation.

Yeah...there are three famous cases that I can remember. The first (that caused them to leave Abbey Road) was that some journalists paid of people at the studio to come in when the band wasn't there and record playback of what they had over the speakers in the control room. The second was again a journalist that recorded (maybe even over the phone) from the playback DYKWIM to a radio station by a guy hired by Creation to go around and hype it up ahead of time (like it needed hype). The third was a guy who claimed that he heard a tape (possibly the aforementioned one made at Abbey Road) while on holiday in Spain during the Spring of 1997 before its release. Then there was this:

Exhibit A to anyone who doesn't think Oasis was a big deal back in 1997.

It's the same date Sgt Pepper was released and also it's the same date as Noel's birthday.