This seems to prove that it is kinda random.
We were speculating that only people starting with numbers were getting it and that alphabets would come later.
I believe alphabets started coming in, and then this invitation that starts with a number.
Yep, I'm willing to stick my neck out and say it is probably random.
We have a pretty small sample size on this community so trends can be gauged, but at our own risk.
We have invitations for people whos confirmation numbers started with numbers.
There was also speculation that they were in some way "sorted" and then sent out in batches.
OK, if that is true, then the sorting would be a regular alphanumeric sorting which goes by the ASCII character sheet.
In the ASCII character sheet 0 comes before any of the other numbers (48-57 on the table). A to Z come in much later (65-90 or 97-122, depending on caps or lowers)
I've read messages where people with numbers starting 2-3-4 etc. received it a day or two ago. If the sorting is computerised, then it would generally put 0 before any other numbers and alphabets.
Since a person starting with 0 got it today, it breaks the computerised sorting pattern theory.
So I'd hazard a guess to say it is random at this point.