Don’t have Evoking Eternity, but my opinion is that yes, you can perceive the spirit in your mind regardless of where it physically chooses to manifest. But, I if it chooses to be in the corner and you see it there, I’m not sure you can physically move it with your mind to be right in front of you.
When I invoked/evoked Set I wasn’t focused on him being behind me. I was sitting on the floor facing forward and at some point began to see him appear off toward the left of me. I was focusing mostly on the words and symbols I had out in front of me. But yes, I felt his presence–thought it was gonna kill me as I’ve posted elsewhere.
I suggest if you’re a beginner (based on your question of where to focus), maybe pick a different spirit to go with while learning evocation basics? Otherwise, if you’ve been around practicing for a while and this question was Just about this entity (Set), then do whatever feels best.
Here’s my post on it (I love talking about Set if you wanna talk):