You know their favourite restaurant, what happened with their ex and their most embarrassing childhood story. But do you know how much your partner earns?

Money remains one of dating's trickier conversations. Bring it up too early and it can sound like you're sizing up their bank balance. But leave it too long and you could be planning a future with someone without knowing much about their finances at all.

We spoke to 20-somethings in New York City to see if there was a sweet spot for when to talk salaries.

Willa Morton, 25, says she doesn't think couples necessarily need to reveal their salaries at all.

"It's just a number and you can gauge how much someone makes based on the way they live and how much they spend," she says.

Willa, who works in tech sales, has talked to her boyfriend about not earning very much herself but hasn't asked him for a figure in return.

He's a company founder and, though his income varies, she knows that he earns more than she does.

"He's more free-spending whereas I'm always saying, 'That's too expensive, that costs too much, we don't need to spend that.'"

Their dates typically cost around $200 (£150) and he usually pays, while she picks up smaller bills such as coffees.

"It's an unspoken rule that he will pick up the bigger bills."

For many, there's a fairly clear dividing line as to when you talk about salary, spending habits and debt and that's when you become an official couple.

Alexa Ludato, 25, who works in insurance, says she'd only have the conversation when she was official with someone.

Before then, she would "like to have an idea of what their job is, but not how much they make".

Her friend, Vik Sunderaj, 22, agrees. "You should only discuss it once you get into a serious relationship."

He thinks a salary question on the first few dates is "a little crazy".

"If they asked, I would be honest, but I wouldn't bring it up," he says. And if his date really wanted to know his salary, "it probably means they wouldn't be the right person for me".

Others feel even more strongly about being asked too soon. Twenty-six-year-old Bridget Shurdut, who works in sales, says she would find it "incredibly odd" if someone asked about her salary within the first few dates.

"I don't think I'd continue to see that person. I'd answer the question, but it would be a red flag for me."

For her, someone's current salary isn't necessarily particularly useful information anyway as she says she's much more interested in "whether someone is ambitious and driven than what they earn monetarily".

Dating and relationship coach Kate Mansfield, says money conversations "should start much earlier than many people think".

"In the first few dates you should talk about how each of you approaches spending, saving, generosity, lifestyle and financial independence as these things shape compatibility."

Becoming official doesn't necessarily mean swapping payslips though.

Insurance worker Emily Moretta, 26, has been with her boyfriend for two years and says they still haven't explicitly told each other their salaries and "he doesn't know how much I make".

She assumes he probably has a rough idea, but says neither has ever felt the need to ask.

"Maybe down the line we would, when it gets more serious," she says, adding that they would have to be at the stage of moving in together before talking about it.