With the cost of butter these days, I have to find it when it's on sale. I recently had some butter go rancid. Yes, it happens. Especially when it's unsalted. Seems the salt is the curative that keeps it fresh longer, even if it's not as good for you.
Now I get what I can afford, and if it's salted, I just don't use as much. I then put my oldest butter to the left and in one direction. Any cut sticks are on the left and in front.
The newest is on the right, going the opposite direction. This way, I am not opening new butter when I need to use the oldest first.
I hope this helps you.
Source: My slightly "over focused" brain!