I have heard Baba Virendra Dev Dixit saying in VCD* 524, that Purushottam Sangamyug starts 1966 when the declaration for 10 years is made and, in the minds of some Brahmins - who are the highest souls, it starts to get revealed.
If Purushottam Sangamyug is in Madhuban then what is in Kampil
Madhuban is rememberance of Shrinath - elevated souls are gathered and Kampil is rememberance of Jagadnath - all souls of the world are gathered.
It is also said in one Murli that Purushottam Sangamyug is of 50 years.