There is no set number, sorry as it depends so much on what you dust and gutload the insects with. If you feed smaller insects you can feed more (smaller are a bit more nutritious and easier to digest anyway), but remember females do start developing infertile eggs regardless of males present or not. To avoid overly early egg development, large clutches, and problems depositing larger eggs you need to be careful how much you feed. She may start egg follicle development pretty soon. There are several good sites about chams in general and about veileds you should read. They are listed below. Their advice is good, so you can trust it. Get rid of the tank ASAP. Don't worry about feeding twice a day. At her age her growth rate is probably starting to slow down anyway. She won't starve! Also at about 6 months you should consider feeding every other day. A good rule of thumb for how much to feed is to look at the base of her tail. It should be smoothly oval from top to bottom. If it's round she's too fat. It is normal to see ribs slightly when she's moving around.
http://www.chameleonnews.com (some good recent articles on veileds)
http://www.chameleonjournals.com
http://www.calumma.com
http://www.adcham.com
http://www.geocities.com/ccicenter