When did Idina Menzel start singing unprofessionally?

It seems like you're asking about when Idina Menzel started singing, not when she started singing "unprofessionally". Idina Menzel has been a professional singer since she was a child.

Here's a bit about her career:

* Early Years: Menzel started singing professionally at a young age, performing in various school productions and local theater groups.

* Broadway Debut: Her Broadway debut was in 1996 in the musical "Rent", where she played the role of Maureen.

* "Wicked" and Recognition: Her breakout role was as Elphaba in "Wicked", earning her a Tony Award nomination.

* Film and Television: Menzel has also had a successful career in film and television, lending her voice to animated films like "Frozen" and "Encanto", and starring in shows like "Glee".

So, Idina Menzel's career has been focused on professional singing from a very young age. There isn't a point where she was singing "unprofessionally" in the sense of not being paid or not taking it seriously.