When is Togepi's Ability in Soul Silver determined?

Question

I've recently began playing Soul Silver again and I was wondering when I should save to get a Togepi with Serene Grace. Is it's ability determined when you receive the egg from Mr. Pokémon or Professor Elm's aid? So should I save before entering Mr. Pokémon's house or before exiting the gym?

Answer 1

When you receive the egg from Mr. Pokemon, it's not actually an egg - it's actually a Key Item, so that should have no effect on what kind of egg you receive in the future. You will actually receive the egg from Elm's aide, which is the point where you want to save. The egg's characteristics are determined once the egg is received.