Vocabulary

Well, there is choir practice for adults and older children, but usually for smaller children, story time includes singing nursery rhymes and other story songs.

I think I didn't convey the idea properly. What I need is your assessment about the use of the expression " It is time to sing" as the anouncement of a period of time in which everybody is going to sing songs. I mean, if you want to anounce children that they are allowed to play from that moment on , you can say: " it is play time". If you want to anounce that you are going to tell a story, you ca

It's karaoke time!
Its sing-along time.
It's lullaby time.
It's time to sing around the campfire. (camp songs)
Let's sing some of our favorite folk songs

http://voices.yahoo.com/10-best-songs-sing-around-campfire-4134839.html?cat=11

Thank you.
Considering the fourth one of your examples, I'll take the 'time to sing' structure as possible, apart from the '(noun)' ones.

This kind of statement would often be used in a law enforcement context: "We've got the goods on you and your accomplices, so it's time to sing [i.e.: confess your involvement in the crime] big boy, before we pin the rap all on you."

Anonymousbefore we pin the rap all on you.

What does 'pin the rap' means?

Stassri Anonymousbefore we pin the rap all on you.What does 'pin the rap' means?

Accuse them of a crime. "rap sheet" = list of crimes that a person is accused or convicted of.