Well I change my clock before I restart my game so it doesn't affect it.So true! You can't imagine how happy I was when the second Pokémon I encountered there was a Cryogonal, and that was in autumn.
And I don't like changing the clock, since it messes up your Black City / White Forest stuff. I had to change it for DST last week, and all the grass in White Forest was gone when I finally got there. There was only the Pokémon Center and that house in the lower left full of useless people (apart from those triple battlers).
Now I have to play through Black to use the Entralink and get it working again...