The reality is that there is no good time for a large-scale platform to go down. I'd speculate that 8am PDT would be worse for Heroku, as their business seems l

The reality is that there is no good time for a large-scale platform to go down. I'd speculate that 8am PDT would be worse for Heroku, as their business seems largely split between the US and Europe, so downtime then would upset everyone... but that's just speculation. You can't build a company of developers selling products to developers while fleeing the working hours of developers.