On left is a true Y. On right is a plant that has been pinched and has grown branches from leaf nodes.
One can cut above the Y and the plant will flower more quickly next season because Y formation is the precursor to blooming.
If there isn't a Y, one may be able to see when a Y might be forming in preparation for blooming because the leaves become asymmetrical. I can't recall the exact word for it right now, but it looks like this.
Leaves that are concerned more with plant growth are even across the base where they meet the stem, like this.
