I may be barking up the wrong tree, if so i dont mind being corrected.
Presuming that the star concerned has already reached supernova 1000's of years ago. Apparently it looks like its going to go critical, so i presume it will have done a long time ago.(Because of the time taken for light to travel....)
If it was to do us any harm it would it have done it by now.
I say this not knowing which is faster light, G rays, X rays, blast or magnetic effect.
I guess magnetic effect the faster of the above.
So it could have happened in the stoneage. We could have felt the effects in the middle ages and see it tomorrow
Like i say, i may not have the facts right