Customers send buying signals from the moment they agree to meet with a sales person. They'll tell you what they want, what they need, what they have filling that need right now, and why they are considering a change. They'll ask for a delivery or in-service date. Is that the right moment to close the sale?
The answer is, only sometimes. We want happy customers. They become our advocates and sources of repeat business or referrals. Still, no one wants to feel like they are part of your agenda. So when they ask, "when can we take delivery" or "what kind of deposit do you need" or "how do I bring my people up to speed on this" or any other classic buying signal, it's time to stop any overt selling. They're sold. It's time instead to educate and advise. That will help ensure a happy customer.