As of 5/17/21, rules have been updated to include timing for runs.

The starting frame is on control of Bonk after the crying animation. This should be ~21 seconds after pressing start at the title screen. Note; there is a brief window where inputs do register before that animation so you could inadvertently delay the start.

The ending frame is when the Drool-mobile explodes (screen will stop scrolling and there is a visible explosion). Previous runs have been grandfathered in as there were slight differences in the end frame (Bluebomberino's WR of 25:35 would still be accurate regardless).

To clarify (since my latest PB is right on the edge of the second line), is the start defined by the first frame Bonk changes from looking at the screen to facing right? Or the first frame entering the walk animation?

For now I will assume it is the first frame facing right but just wanted to clarify for the future.

The end frame seems a little more clear, being the first frame where a small explosion is visible on Drool's car.