There isn’t any. A year or two or three after a major loss is just a drop in the bucket, believe me. There is no time after which condolences are no longer appropriate. Sadly, at some point in your life, you are likely to find this out (we all do, sooner or later) and you will probably want to eat your words. I did when I found out. I judged people who were “still grieving” after what I thought was too long. And I wanted to refer them to therapy, too.
You probably wouldn’t say the standard, “I’m sorry for your loss” that one says in the immediate aftermath. But “how long has <the person> been gone now?” is a question that someone might welcome. Because I’m sure they’re thinking about it, but afraid to bring it up to judgmental people like you (and like I was). After a certain (too short) period, people will stop mentioning the deceased at all-- like s/he never existed.
My husband died 19 years ago, and I am still extremely touched when someone remembers him and says something like, “I still miss him,” because I still do. Most people think what you’re saying (and I did, too, until I became a widow), namely, that one year or at best a few years is “long enough” to mourn someone and surely they’re “over it” by now. But for the loss of someone really close, you never get over it-- you adjust, you absorb the event, you realize that *others *have moved on so you accept that your loss is no longer something they think about. I don’t miss my husband the way I did those first few years, but I still think about him every day and frankly, I wind up mentioning his name just about every day-- quoting him (he was a Texas Aggie, so very quotable!) or citing some event involving him. And at certain moments in certain places, I can still cry over missing him. And I believe those tears are not a sign of mental instability but are a tribute to him.
The first FEW **YEARS **after someone’s death are very raw and painful. I know at least three widows/widowers who lost their spouses around three years ago and their friends have definitely moved on. Some friends are worried and also judgmental, thinking surely they’re over it by now. One of these widowers lost his partner to suicide-- heard the shot and found him with the gun, blood everywhere. Will he ever “get over” it? I don’t think so. After a year or two or three, people are still in the depths of very fresh grief. Especially when the holidays come around, and birthdays, and anniversaries, and other annual milestones. Eventually these milestones are less painful, but you don’t forget.
I’ve had people who lost their mothers many decades ago say to me, “I still miss her every day.” What a tribute to that mom… or dad. And yes, a tear may be shed. That’s not pathology. That’s human.
Why don’t you ask around? Ask some of the people who’ve had these losses. Do it in the spirit of research. “I don’t want to make you uncomfortable, but how do you feel about people acknowledging your loss years after it happened?” Don’t take my word for it.
One day you won’t have to.