Kuddle
Hey Mahima,
It's advised to not collar the young doggos as they are in their growing stage and if they accidentally wander away and they have nobody to take care of, they will outgrow the collar and it will begin to choke. Collar only mature adult doggos with a 2-finger gap between the collar and their neck. If they are not comfortable and not letting you approach them, start slowly and feed them for a few weeks and gradually they might permit you.