I've played through Green Grove and Rusty Ruin and have come up with some times that may be good to use for the time challenges. I've played through each level enough times to get a good feel for them. I will update this post with the rest of the game as I play on.
Video Guides (https://www.youtube.com/playlist?list=PLAR-wm7AwOE5LvZwULnr9T4kegYmbp9Ph&disable_polymer=true)
Green Grove Act 1 0:30
Green Grove Act 2 0:50
Green Grove Boss 0:40
Rusty Ruin Act 1 1:00
Rusty Ruin Act 2 1:10
Rusty Ruin Boss 0:45
sxsxxqq