When should the stimulus be used with the customer and when should persuasion be used? And why?

Thanks for this good question which lead me to a deeper reading.

Cialdini published the six principles of influence in his book “Influence: The Psychology of Persuasion,” and during his studies, prior to his book release, he spent years watching successful salesmen and marketers at work, asking the question, “what makes people buy from them?” I recommend every sales person to read this book.

 There are four moments of truth for a product or service: 

1- Stimulus. stimulus is the moment which occurs when the customer is first exposed to your brand via an ad or piece of content (blog, info-graphic, video, podcast...etc 

2- Zero moment of truth or (ZMOT): This is when prospects recognize a need and goes online to gather information regarding a potential purchase. 

3- First moment of truth or (FMOT).When a customer is confronted with the product in-store or in real life. This represents the a-ha moment when confronted with the product and related alternatives, assumed to be in real life.

4-Second Moment of Truth or (SMOT):When a customer purchases a product and experiences its quality as per the promise of the brand.  This moment happens after the customer has bought and started using your brand or product. 

Sorry this article needs a lot of time to talk about.... I would like to let other colleagues to write about it.

I agree with the excellent teachers  answers 

when you saw that the customer is interesting about the promotion but not ready enough to take decision. here, you can interfere to provide some information or to answer some of the customer's questions to clarify the promotion for him, but don't push him to buy