In my experience there is no special prayer, invocation or guide to communicate with angels. I don't know if you know but we humans have been given the gift of free will.
This means that we are all free to choose and make our own decisions. That is why the angels cannot interfere in any area of our life, without us asking and giving them our authorization.
There is no special time to start communication with these divine beings of light. When you feel ready to have a relationship with them just tell them what really comes from your heart and they will enter your life.
I want you to understand that angels cannot make any decisions for you, they are only a guide to make your life fuller and full of love.