Are some times better than others to perform certain tasks?

You're question to me is closely related to how to work efficiently. Brian Tracey's book "Eat that Frog" and "The Power of Self Discipline" are great ways to help people determine what time of day might work for them. In general his books point to doing the toughest tasks first and getting them over with as the best way to be efficient. Working first thing in the morning, when you get to work, is a great way to get a large chunk of work done before things get busy and meetings pile up. I"m a morning person, so this works for me, for some who are more late night folks, doing tasks later in the evening may work better.

Good question. There’s no immutable rule that dictates when it’s best to perform any task. As a Project Manager you must decide when it’s best to perform tasks based on such factors as business and technical constraints, your organization’s culture, and your resources’ personal preferences. There are any number of guidelines available that advise when and how to perform tasks, but only you can judge whether they will benefit your project.
For example, there’s an Agile guideline that states teams should have a standup meeting every morning. This is generally good advice because morning meetings enable team members to coordinate their efforts at the start of the day, thereby avoiding the risk they would waste hours working at cross purposes before discovering their error. I modified this guideline for my team of Developers, who aren’t morning people and prefer to start their day around 11 am. Instead of forcing them to attend a standup meeting at 9 am when most other teams in my organization are holding theirs, I hold their daily meeting at noon. In this way I achieve my goal (a coordinated team) without imposing a needless rule upon anyone. Being flexible regarding when tasks can be performed can greatly increase people’s satisfaction with the project, and encourage their willingness to take personal ownership of the project.

George:
New practitioners will be dealing with learning the technical and leadership competencies as part of the PMI Triangle. Focus on consistency, repeatable best practices and processes will help all new PMs. It's good to have a checklist, a list of your top three priorities to accomplish daily and focus on reflection daily to review what you've learned. Time Management is important so carve out time blocks daily to perform necessary or time oriented tasks. Don't let other manage your calendar; block out time for yourself and focus on getting priority tasks done first.

You're question to me is closely related to how to work efficiently. Brian Tracey's book "Eat that Frog" and "The Power of Self Discipline" are great ways to help people determine what time of day might work for them. In general his books point to doing the toughest tasks first and getting them over with as the best way to be efficient. Working first thing in the morning, when you get to work, is a great way to get a large chunk of work done before things get busy and meetings pile up. I"m a morning person, so this works for me, for some who are more late night folks, doing tasks later in the evening may work better.