Harvesting Chives

I just had a question about harvesting chives. I started some chives from seeds and they've turned out great. The 'leaves' now are about two to three inches (5 to 7 cm) long and about 2 mm thin. Should I be harvesting them to promote further growth or is there a time when I just allow it grow without harvesting. Just wanted to make sure.

You can begin to harvest your onion chives when the leaves are about 6-inches (15 cm) long. Using kitchen scissors, snip them about 2 inches (5 cm) from the earth. Take only about a third of the leaves while the plant is still young so it can continue to grow. You may want to transfer clumps to larger pots as the size of the pot and amount of soil will limit the growth of the plant. If using clay pots, you will need to water more often to keep the soil moist (not wet...herbs do not like wet feet!). Indoor herbs need at least 5 hours of sunlight. Keep in a south facing window, turning frequently so all sides get exposure. Supplement light in dull winter months with grow lights. Avoid cold drafts from windows at night; move away or draw curtain in front of plants.
You will want to transplant your chives to the garden in the spring, just after the frost is gone. Plant in clumps of about half a dozen bulbs, about 8-inches apart (20 cm). Chives are perennial and prefer sun (although they will tolerate some shade), and well drained soil. After 3 years clumps need to be divided. Chives grow from the centre outward, so harvest from the outside in.
In the spring (probably not until the next season) plants will produce light purple (onion tasting) flower heads which can be broken up and used in salad or to garnish soups, in herb butters, and to make a beautiful pink vinegar using white wine vinegar. (Please see xxx on how to make herb vinegars.)
TIPS:
* Use kitchen scissors to "snip" fresh chives.
* Chives can be snipped and frozen in plastic freezer containers when not in season.
* Chives are a part of the classic herb mixture "fines herbes" along with chervil, parley and tarragon
* Onion chives, usually just called chives have slender, hollow leaves, while garlic chives have flat, grass-like leaves and clusters of star-shaped white flowers.