How often should I let my child (a toddler) eat candy?

Ermmm as little as possible? Make it a treat when a child gets candy not a norm. Maybe they can get candy during their birthday, a special holiday, either on Saturday or Sunday. At such a young age, toddlers and too much candy often lead to all sorts of detrimental consequences -- tooth decay, obesity, sugar rush (I've seen this on my friend's toddler -- not fun AT ALL when the sugar high dies out).