ExH lives overseas. DC live with me. ExH comes back every so often for the weekend to see them, but not regularly. He saw them at Easter and will next see them mid August. He also will see them in some of the school holidays, but I don't know the dates. I also don't know the arrangements for Christmas. As I am here all the time for them, I seem to just have to wait until he decides when he is seeing them. My question is- what is a reasonable amount of time in advance to know the dates?