It also depends where you are playing. A custom character in the Summer Isles (or even Naath, so long as you keep Naathi as your culture to avoid the killer butterflies) doesn't care about the Seven Kingdoms (although slave raiders from Essos may cause problems).
In general, I'd note that early dates tend to have Dragons running around willy-nilly and messing with rebellions.
The only ones I'd especially suggest staying clear of are the Ninepenny Kings, as that has a strong tendency to end with the Seven Kingdoms inheriting part of the Stepstones (which looks ugly), and the last two bookmarks (if you don't want to be forced to fight the Others before you've had a chance to do whatever your goal is for that playthrough).