The pokies are usually the bobbin thread coming thru to the top. It can really be noticable when using two different colors of threads.
If you are going to use two different threads it is recommended to use polyesther batting. Or an 80/20 batting as these are a bit thicker and have more loft.
Also, you need to adjust both the bobbin and needle tensions. It is difficult at best to get them perfectly balanced for this but getting close is acceptable.
For the bobbin, adjust the case to where you can pick up the bobbin and case with the thread and have the case crawl down much like a spider. Then adjust the needle tension, set it a bit on the tight side so you will see the bobbin thread come up and keep loosening until you can just barely see the bobbin thread on the top side. When you start quilting the bobbin thread should be just right then.
Using just a thin batt like W&N will not accomplish the look you want.