When it comes to losing a spouse

How long did it or would you say would be long enough to get into a new relationship? I know the grieving process is different for everyone but just wondering as far as being careful getting into a new relationship and moving rather quickly.
Just asking cause I have a friend who is involved with someone who's spouse has been gone not even a year yet. Pretty close but not quite. So I don't know what advice to to give. Never been in that situation to be able to so I just leave it alone. Although I would think both people involved need to be careful and take it slow with it only being year just about. So just curious is all... Lol I say that a lot at the end of my posts.. Lol