I'm reading that they can be toxic to some animals (birds & reptiles). Don't let him eat any more.
Hope he continues to do well. @Andee do you know more?
Lady bugs are predators, but depending on the species (most different colors are different types) eat different things. But overall, yes they are toxic. But I am assuming you are talking about your adult (sub-adult) veiled? Likely three won't be an issue, and most toxic insects have a bitter taste and usually chameleons or generally reptiles won't continue to eat them. So the species he ate may have not been feeding on something converted into toxicity in it's body. Just keep an eye on him, I wouldn't expect it to take more than a few hours to show symptoms of toxicity, but I honestly would not be worried. Try to flush his system as best as possible with lots and lots of water. A shower might help or a super long mist.