Route: AUH-LHR
Class: Y to J (original booking was a miles booking)
Bid: 5050 dhs (on the upgrade dial, this was the default value; I think the minimum was 3000 and the maximum 8000+)
Bid placed: 1 week before departure
Upgrade confirmed: 3 days before departure
I got an email a few days after the initial bid suggesting me to increase my bid, which I ignored.

Route: LHR-AUH
Class: Y to J (original miles booking)
Bid: 3000 dhs (default value)
Bid placed: 9 days before departure
Upgrade confirmed: midnight the night before
As above, I got an email a few days before the flight encouraging me to increase my bid, which I ignored.
I had also booked a chauffeur for the return (one of the Gold "bonus benefits" or whatever its called) before getting the upgrade. Etihad kindly cancelled the chauffeur when they upgraded me, which was a lovely surprise at the airport on arrival.