New Plumbing vents installed before or after shingles

[John Weidner]

Whats typical process order on new construction:

1.  Plumbing stacks go in after roof is closed in with Plywood but before shingles  (Plumber comes in after Framer but before roofer).  

2.  Plumber cuts hole in plywood for roofing vents and roofer installs collar flashing before plumber.  Plumber runs piping after roof is on?

3.  Roofer roofs right after framer and plumber installs vent flashing after roof is on.

Thanks