When it comes to thank you notes, it is never too late, but the sooner, the better. Many people consider it rude not receiving a thank you note, but others prefer later than none at all. Most people understand the first little bit of marriage can be chaotic especially when there’s packing, moving, unpacking and reorganizing involved. So they expect a little bit of a delay but not too long of one. So it is always proper to send a thank you note.