This is one of the top 3 reasons why reps don’t get the business. They just don’t ask for it.
Don’t focus on the outcome, focus on the process. If you’ve done the right things in the right way, it becomes your professional responsibility to be assertive.
When should you close? Early and often! Asking for little commitments along the way makes asking for the final commitment much easier. Plus, you’ll learn very quickly how real the opportunity is. Customers who are unwilling to make small commitments along the way are going to be even less enthusiastic about making a bigger commitment later on.