Is the Mesclun ready?

This is my first year growing any vegetables. I took a stab with a couple varieties of mesclun, as we love salads, and tire easily of the traditional lettuce. This is my mesclun, which I started from seed in the greenhouse at the end of March, then moved them to the vegetable garden when they were about 3 inches tall. Now, they're anywhere from 10 inches to 18 inches tall. I've tried one of the leaves, and it tasted pretty good, but I'm not sure if they are in fact ready to cut. Also, what is the best method for cutting? Do I pull the plant out entirely, or cut at the bottom, and let it regrow (if it does)?

Thanks much for any help/suggestions.

Another view of the mesclun.

With mesclum there are several ways to use it. You can use the whole plant when small for baby greens. You can cut the greens with scissors(this is called cut and come again method) or you can remove the large outside leaves or just wait till it's big and cut the whole plant for use. Don't wait too long though or the plants will bolt (go to seed).
Here is a nice link with lots of information http://www.ngb.org/gardening/fact_sheets/fact_details.cfm?factID=12

It looks like some of that may be bolting already. When I was growing it I would pick it when it was 6" to 8" tall, with the heat here it bolts early.

Some of them do have flowering shoots on them. Guess I should pick them and use them now. I didn't realize it was already ready. Thanks much!

That stuff in the first photo doesn't look like any lettuce I'm familiar with.

Lettuce bolts easy here. Also it's a mess to clean, I stopped growing it accept for doing it hydro style.