He shows up after day 68 as long as most characters in the journal state "Wait for the boss".
You need to have unlocked the laboratory for the boss to show up.
Are you stuck somewhere? Visit a bunch of other girls.
I have almost all the characters saying to wait for the boss except the following:
Rose (meet in room after stacy)
Nani (this is it for this version)
Mother teresa (meet her after progressing other character storys)
Stacy (unlock story after 60+ days in mansion complete mia)
Eva (this is it for this version)
I also have the lab unlocked. is there a specific place I must go/return to for the cut seen to trigger?