don´t celebrate it before

My birthday this year was on a Wednesday. I have my German class on Tuesday and Thursday. I figured the class would be a great excuse to make an American cake with frosting etc. I opted to make the cake with the kids on Monday and bring it into class on Tuesday. Of course, I thought it would make a little more sense to bring it on Thursday, but Monday we had the time, I didn´t want to spend my birthday making my own cake, and there are more people on class on Tuesdays. Anyhow, we made the cake and Reimund came home and was said "Hey, what´s this?" I told him and he said it would have made more sense to bring the cake on Thursday. I explained why Tuesday was better, and while he accepted it, it still didn´t seem like a sufficient reason. I chalked that one up to Reimund liking things the way he likes them, but then I got the same reaction from my German teacher. I came walking up with the cake on Tuesday morning, and she said "Oh, I thought you were going to bring it on Thursday, after the actual day" Are you kidding me? I make cake for the whole class and they aren´t happy with the day I brought it? This was too much. But apparently Germans DO NOT celebrate the birthday in any way shape or form before the actual day. My teacher specifically told me she wouldn´t say happy birthday until Thursday after it actually happened. Really I wasn´t looking for anything other than to make an American cake... oh well, learned my lesson, from here on out you really don´t talk about or do anything for it before hand. whew!