How quickly do you send thank you notes?

I aim for getting them in the mail less than a week after the event but definitely fall short of that at times... It seems like the longer time goes on, the harder they are to write! I think it was nearly a month after the wedding before I had the thank you notes out (I know, I know...)

But, I'm redeeming myself! My baby shower was yesterday and I just sealed the last thank you note, I'm putting them in the mail tomorrow.