It is based on the time zone that you are in.
That is, if you move time zones then the time on the invite will change according to the new time zone you are in - so you need to convert it to the time zone of the location the EX is in.
EXAMPLE A friend got an EX invite for our local park while interstate. He sent a screen shot of it, but the time was out by half an hour as it was shown in the time zone of the state he was visiting.
