Well...Such ages are only know within a few thousand years accuracy, but the youngest remnants knows are

CTB 109        10,000 years     10,000 light years
Cygnus Loop    20,000            2,600
W50-SS433      30,000           15,000
IC 443         60,000            5,000
Gum Nebula     10,000            5,000

Young supernova are very easy to see as X-ray and radio sources, but they age very rapidly and become unobservable within 100,000 years.