To summarise the rules on
transmission of EAT by ATC:
If it is anticipated that the aircraft will have to enter the hold for 30
minutes or more ATC must pass an EAT by the most expeditious means to the
aircraft.
If the expected delay is 10 minutes or more the EAT must be transmitted to the
pilot as soon as practicable. The pilot may be able to absorb that 10 minute
delay en-route and avoid entering the hold.
If the EAT changes by 5 minutes or more ATC must pass a revised EAT.
'No delay expected' means that the aircraft could still be subjected to a delay
of up to 20 minutes before being cleared to make an approach.