berlin qualifiers start?

does anyone know when the challengers stage 3 start to qualify for berlin? or around when they could start

MAYBE JUNE 1ST OR 2ND

AND THE MASTERS 3 BERLIN WILL BE HELD IN SEPTEMBER IF I REMEMBER

challenger finals should end in the first week of august.
so before that there are like 6 weeks of play and 2 weeks pause. probably gonna start around 10th-20th june. for NA it should be 11th or 18th june