Between 12-18 months
Step-by-step explanation:
In this stage the infants are considered to be in their tertiary circular reaction stage and the baby will start to explore the objects and they will try the new ways in exploring them and they will start to try to reach out the objects
There are many stages of sensorimotor which will lasts still 24 months and there are also six sub stages in which all the primary the secondary and the tertiary reactions will be coordinated