Salespeople have all kinds of superstitions around when they should make certain kinds of calls.
Some salespeople refuse to make cold calls on Monday. This group believes that the last thing anyone wants is a call from a salesperson first thing out of the gate Monday morning. Others believe that Mondays are the very best possible day to make their calls. They believe that people who want to get things done take those calls so they can schedule an appointment to take care of something important.
Some salespeople believe that Monday is the very best day to call your existing clients. The logic here is that you can ask them about their schedules for the upcoming week. Others believe that Friday is the best day to call your existing clients, after their clients have completed their tasks for the week and created some breathing room for them. So, who's right and who's wrong?
The arrogance of reading minds. The truth of the matter is that no one knows the best time to call. How could you? Some of your dream clients might have a project you could help them with staring them in the face on Monday morning. Your call might be just what they need. Or they might be so overwhelmed that the sound of the phone ringing is enough to put them in what we might call an "unreceptive" state.
It's a certain kind of arrogance to believe you can read your dream client's mind. You can't. And as soon as you start to generalize about a giant, diverse group of people, you are automatically wrong. Each individual contact is dealing with his or her own life, with individual agendas and communication preferences. There is no way you can know their minds, and it's a waste of time to try.
Making calls now is better than making calls later. The sooner you make the call to your dream client, the sooner you begin to open the relationships that can open opportunities. Even if you fail to 
