I just had the OEM pads replaced at 75,000 miles. For the last 28,000 miles, part of my daily commute has been downhill on a canyon road so I knew I had been using them more than when I was on the freeway.
I think I was at 1.5mm so I probably had a little more left but William at Valencia Honda made me a deal I couldn't refuse! (Calpod knows who I mean 8) )
as soon as the brake lights come on its regen only. there are some threads on here about the "max regen" mod, basically a switch that tells the system you have pressed the brake pedal, so it kicks in full regen.
Mine only got about 32k out of the original brakes. They had plenty of pad remaining but had been over heated by the original owner and the disks were warped. Replaced by a set of Autozone pads & rotors and have been fine so far.
Front brake pads replaced at 100,000 miles as a matter of preventive maintenance. Old pads were well within the "wear limits". Still have the original rotors on the vehicle. Have owned the vehicle since new and now have 176,000+ miles on the odometer.