Between 12-18 months
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
The most immediate thing you can do is move the player you suspect is in heat stroke (usually they are flushed, and dry, because the heat has compromised heat regulation. They are also more than likely to be down), to a cool, well ventilated, Air conditioned area. You need to bring down their body temperature as quickly as possible. At least if this unavailable move him into a car, blast the A/C, and have a towel soaked with water placed on him.
All of the above :) have a good day!