At what age can I start giving my baby time outs?

18 months. Of course, that really depends. I've had a few of my patients who were able to understand the concept of time out at even 15 months. This depends on the developmental stage of the child. Most children will understand the concept around 18-24 months of age. Remember, time out will not last long; it's only about a minute per year of age.
Around 18 months. Every child is different, but by the late teen months, children can begin to understand the topic. Time out must be accompanied by a brief explanation of what they did wrong, and also a brief time out. One to two minutes is reasonable enough at that age and can be increased by about 1 minute a year.