Answer: Depends where you live in the World
An email conversation with a very nice customer in Australia got me thinking about when Stationery Wednesday is actually received around the World. Having always seen it as a UK based newsletter, it is read globally, of course. So a bit of simple investigation led me to finding out the following.
Assuming that the newsletter is sent at 9.25 am here in London (I do have a target time to send it out, even if I don't often get there), then this is when it is received:
The earliest possible place to receive it would be Baker Island, where it would arrive at a surprising time of 8.25pm on Tuesday. If anyone actually lived there, that is.
The most realistic place to receive it on a Tuesday would be Honolulu, Hawaii - it arrives at 10.25pm on Tuesday. This is the same for Rarotonga in the Cook Islands. Anchorage, Alaska receives it at 00.25am, so that's already tipped over into Wednesday.
If you keep going east, you get to Sydney (it should arrive at 7.25pm), Auckland (a suitably late 9.25pm) and then you are off into the Pacific.
The Chatham Islands have a strange timezone, at +12.45 hours, which means they get it at 10.10pm. To really go for it you would have to go to Kiribati. If you go to their furthest islands you will find Kiritimati which is +13 hours, and so 10.25pm. Sadly there is no-one for whom Stationery Wednesday is already Stationery Thursday.
So the answer is that virtually the entire world has the ability to receive Stationery Wednesday on a Wednesday (if read when sent). Apologies to any readers in Hawaii who celebrate Stationery Tuesday, but just take your time, maybe brush your teeth slowly, and you can go to bed and read the newsletter on a Wednesday after all. The rest of you have no excuse.
NB: This was all based on current times here in London, and since we have just moved to British Summertime (BST) that means we are on GMT+1 hour. I will let someone else work out if this makes a difference or not.