I know that htere’s no hard & fast rule here but I am just curious as to if it makes a difference. ‘To know’ comes before ‘To Will’. Does that imply divination be mastered first?
Go with your instinct but yeah, you might wanna give divination and astrology a try first. These occult sciences might help open up your astral senses so you’re more ready for evocation (the spirit appearing from the outside).
As for invocation, it’s just drawing forth the spirit’s energy so it enters your being. It’s very simple and you can start doing it now. Here’s an example of an invocation: http://theisticsatanism.com/invocation.html
Here’s one more example. It’s a Buddhist chant but I feel it’s similar to invocation.
Namu Myoho Renge Kyo