When to switch from mineral to synthetic oil.

Firstly this is not intended to be oil debate of which brand is bestest!
Recieved mixed answers in regards as to when to switch from mineral to synthetic during break in; so, would someone like to take a stab to put this issue to rest.
Cheers
Recieved mixed answers in regards as to when to switch from mineral to synthetic during break in; so, would someone like to take a stab to put this issue to rest.
Cheers