New Arrival - old ground reassurance

[ichbinnaughty]

Hi all,
I'm a newcomer to this board, having just picked up an X3 20d F25 (production date = November 2011; registered January 2012) M-Sport from a private seller => 62,000 miles, full BMW service history, fully loaded, well looked after.
Checking BMWVIN decoder, I can see it has the N47T engine.

Now, perusing BMW owner forums, as I do, to get myself familiar with what to expect as an owner, I have read with horror this whole issue of timing chain failures that seem to affect various BMW engines of vehicles manufactured before and up to around this time.
So far I have been unable to decipher :
- whether there is a real prevalence of these timing chain 'blow ups' (resulting in complete engine rebuilds/replacements)
- whether there was a subtle design tweak implemented to vehicles after around March 2011
- whether the issue affects my engine type (N47T)
- whether I should be living in FEAR
- what I should do to mitigate any risk (aside from selling it)
- what I should NOT do

I've got to say that two weeks in I have no personal cause for concern - my X3 drives beautifully so far and if I hadn't scaremongered myself by reading the forums I would be living in blissful ignorance. 
I'm just looking for input and responses = specifically to this near-mystical timing chain time-bomb; but also on a more general level - do's, don't's, etc.

Thanks in advance.