The dates I previously estimated commenced in the same week which was;
Japan; Wed Oct 16, UK; Fri Oct 18, US; Sun Oct 20, AU; Tue 22 Oct.
In most cases, Australia usually got new games before Europe. The only times Australia came last was with Red & Blue and Black & White.
I'll probably see the order being Japan, US, Australia, Europe like with HG/SS and B2/W2. I do agree with Suicune that the games should all be released in the same week so that people from certain countries don't get unfortunate spoilers.
I think it's highly unlikely they'll be released near my birthday (October 1) so I guess I'll have to get them for Christmas again, like what I did with Black 2/White 2.
Yup! There has been great speculation from that! I thought that maybe the version exclusives from each game has to do with gender, since X represents male, and Y represents female, so maybe we can see a male rival in X, and a female rival in Y. Though some have also speculated that the 'X' and 'Y' corresponds with the 3D-axis, where you know, in 3-D, there are about 3 directions (X,Y, and Z). So, there can be a possible theme from that as well. Might be a tad tricky, but there can be!
I have seen a continuing trend with version exclusives, they make one game have male-looking exclusives and the other have female-looking exclusives. Take Black/Black 2 and White/White 2 for example. The former had female-looking exclusive Pokemon while the latter had male-looking exclusives.
However, I could see X being the "male-looking" game and Y being the "female-looking" game given I've seen fanart depicting the male protagonist with Xerneas and the female with Yveltal. I will eventually come to a conclusion when the version exclusives get revealed since my main version I play from a paired version usually has female-looking exclusives.
A gender difference for the rival could be a neat twist, but I'd rather it change gender depending on the player's gender, like what they did with Yancy/Curtis in B2/W2, they made Yancy appear if your gender is male, and Curtis if you are female.