How early can a chicken be broody?

[JessHall]

Typically at what age might a chicken begin showing signs of broodyness?
I am getting some chicks today and I was wondering if it was possible for a younger chicken to care for them... it's really hot outside... like 70's at night... or should I scrap the whole idea and stick them in a brooder? Thanks in advance

 

[Year of the Rooster]

My first two started at approximately 7 months.