begining and end of "1 round" duration effects

[jstbell]

when abilities have effects that last for 1 round. (namely misfortune Hex) When does the effect end? At the beginning of the casters next turn or at the end of their next turn.

I had my witch cast the misfortune hex and i figured that since the standard action ended my turn i figure that the effect would last until the end of my next turn. (so i could cackle and extend it and also apply another hex before the effect ends)

My DM disagrees, and believe the effect ends at the beginning of my next turn. Is there some line in a book I could point to in support of my argument?

[Diego Rossi]

PRD wrote:

Unless otherwise noted, using a hex is a standard action that does not provoke an attack of opportunity. The save to resist a hex is equal to 10 + 1/2 the witch's level + the witch's Intelligence modifier.

...

Cackle (Su): A witch can cackle madly as a move action. Any creature that is within 30 feet that is under the effects of an agony hex, charm hex, evil eye hex, fortune hex, or misfortune hex caused by the witch has the duration of that hex extended by 1 round.

Using a hex don't end your turn. If you didn't used your move action you can cackle to extend it in the same turn you casted it.

[jstbell]

But what if you did move before you cast the hex. Does that mean you have a move action in your next turn to cackle before the hex ends?

[Starglim]

1-round effects last until just before the same initiative count in the next round. Generally all of a character's actions happen on the same initiative count. Misfortune would end at the beginning of the witch's next turn.