I encountered a small problem with the module in D7:
when I enter or edit a node that uses scheduling, and I only enter a date and leave the (required) time field empty, I get a validation error on saving the node which is OK.
At the same time I also get a system warning (see attached screenshot).
I've taken a quick look at the code and I think you might have to alter the node_save validation a bit to first check all fields before calling _scheduler_strtotime.
Regards and thx for a great module,