I absolutely love ReadyXwick. I would rather use that than anything else. To use it, you will want to insert something small inside the piece of wick that you cut and wrap your coil around it. Don't try to thread it through the wick. You will end up with frayed ends that have to be cut off (wasting the expensive wick) and very frustrated. I use one of the really long sewing straight pins with the yellow ball end. You can use a large needle of any kind. You will need 14 wraps each coil for 2mm.
You can use only one coil in that RDA. You do not have to use 2 coils. If you opt for one coil, you will make 7 wraps for one coil only. When you have 2 coils, you have to double the amount of wraps on each coil. In other words: single coil only 7 wraps. Dual coil 14 wraps each coil.
Edit: the smallest diameter "rod" in the coiling gizmo you ordered is good for inserting into the ReadyXwick and then manually wrapping your coil around the ReadyXwick. You don't want to make a 3mm coil and put the 2mm wick inside it. This wick does best with the coil snug around it. It is ok that there will be space left inside the wick when you remove the wire or pin. The wick will still be snug inside the coil. A 3mm coil with 2mm wick allows too much space and your wicking won't be as effective.