I don't find it either. There is a larger "Reference Manual" for P610 free at
http://download.nikonimglib.com/archive2/11qSF00ldYhS01DFgyM782eR4z31/P610RM_(En)03.pdf
and it is searchable, so I thought it would be easy to find there, but sorry, I don't find mention of it either.
A lot of settings, you'd think it would be there, but I don't see it either.
There is an Auto OFF, timeout before camera goes to standby, but that's like 30 or 60 seconds, so I think not your question.
Maybe it is a question to ask Nikon support?