GOogled the answer

Solve at least 50 problems as official contestant in Go

yuki20061, first achieved on March 29, 2017

Martynas1, first achieved on Sept. 30, 2017

smalex691, first achieved on Aug. 18, 2017

orb1, first achieved on Oct. 31, 2016

binhuq1, first achieved on Nov. 11, 2014