My DD2's birthday is on 31st Dec and thats when we will be having her party. I know some people will have other plans, new years eve parties ect but it is her day not a week after or whenever suits everyone else so thats when we will celebrate. I know mil won't be there cause she is going camping but its not like she comes to DS or DD1s birthday parties either. I think you should do it on your DDs birthday, its her day and if people don't make it, it is there lost they are the ones missing out.