How to use Enochian calls, which used when?

Hey, all. It’s been a while since I’ve been here. Wasn’t sure where to put this, so move it if need be.

But I’m preparing for Samhain, and I got the idea to write a letter of thanks to Lucifer because he’s done so much for me this year. I got the idea from Tumblr, where you write a letter and then ritually burn it as offering. But then, there’s very little in the way of LHP/Satanism on there so I wondered, which key should I use? Usually rituals require the first, but I just want to be sure.