thanks @fanou as mentioned in my post I already tried this exact approach using hour hh:mm instead and it is not consistently performing. I am using an almost identical prompt. Relying on the collect prompt for formatting only works about 50% of the time when I test it with GPT4.
I need times (8:30pm) as well as relative dates (tomorrow, this Friday → converted to a standard date format). These are use cases I know duckling is typically used to handle but hybridizing LLM slot extraction with duckling seems unsupported