Default date and time for date/time field in custom module

Default date and time for date/time field in custom module

I have a date/time field in a custom module.

When creating a new record I have to manually select today's date and the current time in the date/time field.

Is there a way to preselect today's date and time when creating a new record in this custom module?

eg. Could this be done with client script? Or a workflow?

Thanks.

Marcus