Is it too early for christmas cards?

I reaally don't think so. Most of the big stores are even now beginning to stock their shelves with christmas goods, and after Halloween they will have many more feet of shelf space. Here are a couple of cards from my Zazzle store, both using vintage images:-

snowman and children christmas greeting card by ArtyfaxCards
View Snowman Cards online at zazzle

snowflake christmas card by ArtyfaxCards
Add your photos and text to blank greeting cards at Zazzle

winter scene, sleigh ride card by ArtyfaxCards
Browse more Snow Cards at Zazzle

I also have many other cards and gifts with similar images, why not take a look, you might be pleased that you did.