how long before i spring a Leek?

I was given two dozen little leeks in late spring, not sure when they were sown, or the variety, they are now looking really good, big and strong. some of them i have put in tubes and some not and some went to seed in the middle of summer which i removed. I would like to know when i need to be pulling them, as although some of them look of a good size, i would still like to see if i can get some nice big ones for winter. Any ideas appreciated.

Totty

If they are fat already they were probably an early variety so will be ready to eat now