Yucca harrimaniae, when does this plant usually bloom?

[Merlin]

I went out this afternoon and took a picture of my Yucca harrimaniae that i grew from some collected seed. The largest plant in the picture is actuall three sprouts. all these come from one plant that came up then branched into three and then started sprouting up all over. I am not much of a devotee of this genus so i dont know much bout them but i looked it up and this plant is now over 12 years old and has yet to bloom---is this normal? I plan to rebuild this part of the garden this spring and i dont think i will be able to dig this thing up and move it(it has a huge underground root). I put a coffee can next to the oldes part of this plant for size reference.