Thank You Cards

What's the general etiquette these days for sending out Thank you cards? My understanding is that they need to be sent within a month, especially after Christmas, although that's what would happen in a perfect world... Can I get away with sending the cards out for all of Dumpling's birth gifts four months after she was born? We didn't send our wedding thank you cards out till six months later cause I felt so crap due to being pregnant.

I've tried to be clever with Dumpling's Thank you cards and it's backfired. I wanted to do individual pictures of Dumpling wearing or with each of her birth gifts. We were doing really well but then it turns out that the latest picture paper has "gone off", so about a week after the pictures were printed yellow patches started to appear. They look really rubbish now. So we've got to do some of them all over again. I was going with the approach of sending out 10 a week, but we've still got 15 to go and I know I'm leaving it really late. I just don't seem to be able to get motivated. Dumpling started gurgling back in conversation this week so we've spent most of the week doing that and I just can't be bothered with thank you cards at the moment. I want them done though, cause having them hanging around is bugging me, but it means a trip to a place which sells picture paper and oh it's just too much effort!

I will get to them soon though. Its the least we can do as we received so many wonderful gifts, from very unexpected people too. I guess that's what new babies do to people. Just how far can I push it without being rude?