My SIL was in agreement with everyone on here re my BIL's long-time GF so my niece just called her by her first name.

We live far away and don't get to see them much. They started dating around the time dd was born, and by the time dd could talk I just referred to them as Uncle and Auntie to her. My MIL and SIL kind of pursed their lips about it, but the GF was very touched and took me aside to thank me for being so welcoming to her in the family.

They were a great couple and the GF always participated in things as though she were one of the family. I didn't think they would ever get married but they eventually did tie the knot, making her officially my SIL even though she was already a very beloved person to us and was already like a sister to me.

My niece started using Aunt for her when they got engaged.

I guess some people prefer tradition, but I feel like it's a respectful way to address someone who is a member of the family and I don't think that a wedding is necessary for someone to be welcomed into the family.

When they're married. But my kids don't call adults by their first names only, so right now it would be MISS Jane.

When they are married.

My good friends are called auntie and uncle so I'm looser on the title, I just did it when it seemed natural with SIL

My brother's fiancée has been called aunt since the engagement announcement.

When they get married or if they have been married and co-habitating for a long time (say 10 years) and have a child together, in other words, they are living as a long-term permanent family without a breakup in the foreseeable future. Having now seen several relationships that fit the latter description, they've moved into the common-law husband and wife scenario where they are as committed as I would expect them ever to get.

OP here. OK the unanimity on here convinced me. I have an aunt whose long-term partner (not married) I always called uncle, so maybe thats why it didn't seem necessary to wait till they're married. But waiting is not a big deal either.

In my family we don't really do aunt and uncle titles unless it's too distinguish from another person with the same name, so for us it would be never.

We made the switch after my brother proposed to his girlfriend. DS is only 2 and doesn't quite grasp titles yet, so I wasn't too concerned with the timing. If DS was older and understood the relationship, I'd probably wait until the wedding to refer to her as Aunt.

Anonymous wrote:it would be nice for the kids to get used to the switch

A wedding makes a very easy time to make the switch. "Now that Uncle Jack and Jane are getting married, she'll be your Aunt Jane!"

My answer might be different if they had already been together 5 or 10 years and she expressed an interest in being an aunt to your kids.

When they're married.

no title until she's really Aunt Jane.

Agree with PP, when they get married. If you want something more than Jane for now, what about Ms./Miss Jane?

I wouldn't start until they were married.

My brother just moved in with his very nice gf of about a year. So far, my kids (ages 3 and 5) have been calling her by her name (let's say Jane). When should they start calling her "aunt Jane"? I think they'll end up getting married, so it would be nice for the kids to get used to the switch. But is it strange to call her aunt when they're not even engaged?