That is a fair to middlin sized zuke. In So_cal, we used to find some buried under the leaves that were 30+ inches long.
In Michigan, they get even bigger; left on the vine until first frost, they then saw them off the vine, cut them lengthwise at the local zucchini mill, scoop them clean and shellac inside and out. By spring, they have a new 2-man canoe. ;-')
Any zuke, if left to grow will get huge, and develope a tough rind; best time to pick for young & tender is when the flower bud shrivels and is falling off the end.
The big ones can be stuffed (We like to chop what is scooped out,, and mix it with Italian sausage, onion, garlic, etc; then top with tomato sauce & cheese) like a winter squash; best to par-cook the stuffing, so the the squash doesn't overcook before the stuffing is cooked through. Or you can pick them when they're an in between size, before the skin gets too tough, and slice it in half it lengthwise, like a loaf of French bread; brush with olive oil, then either start topping it like a pizza; or just put cheese(s), garlic, basil, and tomato slices & put it in the oven until done.
Zucchini bruschetta 
Zucchini pizza boats
Stuffed zucchini