Let's just say I'm going last minute and the last day is tomorrow. So that day the Palkia event starts while the Dialga event is about to end. Is there a certain time where it ends? If it ends before I get there I lucked out :/
The event will end when the Gamestop you're going to closes.
Source: I got my Keldeo as it closed :P
America/Canada, at Gamestop:
Dialga obtainable August 19th to September 8th.
United Kingdom, at GAME:
Dialga obtainable August 30th 2013 to September 12th
Australia/New Zealand, at EB Games:
Dialga obtainable August 30th 2013 to September 12th.
Hope I helped!:)
I think the Dialga event stops the time gamestop closes on the 8th and Palkia starts the time it opens on the 9th.
Aug 19th - Sep 8th (USA)
Aug 30th - Sep 17 (Canada)
Aug 30th - Sep 17th (UK)
These are the star and end dates for canada, the US and the UK. I got these off Marriliand.