Debt/Equity Private Placements - Process Question

Very basic question but can someone enlighten me: Is it customary or at all normal for a potential investor in a private placement (private company issuer, not a pipe) to sign an NDA before hearing the pitch? Or after, say, post-pitch but pre-diligence? 

Any other guidance on stages of a private placement: investor outreach, nda, pitch, term sheet, diligence if term sheet is acceptible, closing. Missing anything?

Thanks.