Questions & Answers about Перед ужином я начинаю размораживать рыбу.
Because перед normally requires the instrumental case.
So:
- ужин = nominative dictionary form
- ужином = instrumental singular
In time expressions, перед + instrumental means before something:
- перед ужином = before dinner
- перед работой = before work
- перед сном = before sleep / before going to bed
So перед ужином is the normal grammatical form here.
It can mean both, depending on context.
- перед домом = in front of the house
- перед ужином = before dinner
In this sentence, because ужин is an event/time, the meaning is clearly before dinner, not a physical location.