At what point are you considered "inbound", say after a procedure turn? When the course is "alive" or is it within one dot? And a reference would be great too.

Another scenario:
Let's say you are at 3,000' headed toward TAM from the south.
ATC says: Maintain 3,000' until established, cleared ILS 13.
At which point can you start your descent? After TAM? In PT?



Thanks in advance!