MikeT
Your band saw blad has a lot to do with drift as well.
Every blade has some drift, and that is part of what causes the waver in the cut. If you take a board of similar thickness as to what you want to rip, and draw a straight line down the board, then start to forehand rip it. As you move the tail back and forth to get the blade to rip either straight down the line or parallel to it, it will begin to rip straight at some angle to the blade. Stop and stop the saw. Once the saw has stopped mark the edge of the board on the table top. This reference line is the angle your fence needs to be set at in order to get a nice true cut. It is why bandsaw rip fences have an adjustment for angle. Once you have your angle and width set on your fence, test cut a scrap or two to make sure it is adjusted correctly. I’m sure there are YouTube videos demonstrating this, and likely easier to follow. I will check it out and if I find anything that is just that I will edit and post a link.