I voted "Just make it interesting," but wanted to share my specific philosophy, too.
As you'll note in my longest ones, "Sweet Lands of Liberty"(Waldensian reformation) and the one with Jefferson winning in '96 whose name I forget, I went about a century because it's still more plausible that the same nobility and such would be born and it remained int he same era historically. It is harder for me as a writer - maybe due to very mild Asperger's - to keep coming up with totally different systems, people, etc..
So, because of that, I sort of prefer TLs where the Butterfly Effect isn't as huge, where it's not "everything changes" but "things only change if it's impossible for them not to." In other words, if A could hve married B, they do and hve C, D, and E; more of a historical determinism. This is especially important in sports - hence my "If Baseball integrated Early," where baseball integrated from the start, has the same players but in different situations on different teams.Obviously, they have to be born to play.
That gets back to the just keep it interesting part, though. Sports are more specialized than general history and it's harder to have it be interesting unless you really limit the Butterfly Effect to what must logically be different from the POD. So, if "interesting" to you means keeping some form of socialism when your POD is the 12th century, that's fine, in my view. Or you want to have a genius appear named Ben Franklin in that same TL doing different things, that's fine, too. It's really however you want to do it. As long as there are enough differences to make it interesting, too, the further out you go; in my Waldensian one, for instance, had I continued, having Savoy (which encompasses Switzerland and is a neutral) with a League of Nations prototype housed in it but with a different name and at a different time would have been quite plausible, too, as long as other stuff about it was different.
Edit: It's probably keeping that in mind that keeps me from worrying about being overly zealous in worldbuilding, too; a good majority of the time I'm just using wikipedia or baseball-reference.com (Which is, admittedly, ls better than Wikipedia.)