1. Room Temperature: Ensure that the room temperature is comfortable, neither too hot nor too cold. Baby blankets are primarily used to maintain the baby's body temperature, so they are more commonly used in colder environments.

2. Season: During colder seasons, babies may need to start using blankets earlier. In warmer seasons, you can delay using blankets or opt for thinner ones.

3. Baby's Development and Abilities: Ensure that the baby has enough ability to move or adjust the blanket to avoid suffocation or discomfort.

In summary, the timing of using baby blankets should be determined based on specific circumstances and the baby's needs. It is recommended to consult a doctor or pediatric specialist before using baby blankets to ensure the baby's safety and comfort.