One way to know when the pineapple is ripe and ready to be cut is by pulling on the leaves. If the innermost leaves easily come out, the pineapple is ready to be cut.
Another thing to look for is the color. Pineapples that have mostly yellow some green and some brown are ready to be cut. The unripened pineapples will be mostly green with a little yellow. The over ripened pineapple will be mostly brown with some yellow and almost no green.