At what age did you sleep train your baby?

now when my daughter age 3 we try to train her sleep alone at her bedroom..but shes says she dont want to be alone..😅need mak and ayah to join together with her if want her to sleep at her own bedroom...shes give and excuse if dont see mak and ayah face ...shes feeling really missed us🤣✌🏻😅shes have a lot a reason and excuse dont want to sleep alone🤣🤣😅