Another datapoint. Was flying on a AA numbered flight (operated by AY) USA-HEL and was delayed causing me to miss my HEL-xxx flight. I was rebooked and wound up arriving at my destination about 6.5hrs late. Filled out the EC261 form linked above while on my extended layover in the Platinum Wing, requesting €600. Heard back 13 days later requesting some details to process the payment. Have not received the $$ yet, but was told to expect it to take up to 2 weeks (still inside that timeframe). Was very much prepared to fight based on the comments here, but other than it taking 2 weeks to get a response, I'm happy (assuming the money transfers of course).