No rule is set in stone about how long we should mourn the loss of our loved ones. The worst feedback to give anyone is that it is time they got over it.
Such ignorance serves no good purpose and may upset the mourner and make them withdraw even further. There is no set rule regarding the mourning process and how long it may take. We will continue to mourn our losses until we no longer need to.
The best we can do for mourners is to listen, reassure, and support them. If you are tempted to share your opinion, stop and keep your opinion to yourself. If you want to share anything, then share your love. That’s all that a mourner needs; our love.