How do i tell if i've sung 16 bars yet?

i have an audition next week, and i need to sing 16 bars from "Out There" from Hunchback of Notre Dame (just Quasimodo's solo), "Where is Love" from Oliver, and "Go the Distance" from Hercules.. problem is, i don't know how to tell if i've sung 16 bars of each song yet.. where do i stop?? i really want to get this, so please please help me on this one!! thanks in advance!!!