Maternity leave commencement

Hi everyone! I am due with our 1st baby, a little girl, on the 6th of December. I’ve got enough holidays left to, in theory, take annual leave from the 6th of December until Christmas, go through the Christmas break & only start my mat leave in January, if this is allowed at all? Or does maternity leave have to start the moment my baby is born? The reason I’m asking is because my company pays 6 months of fully paid mat leave so if I could take it from January only I’d technically be paid fully paid for 7 months from the moment our little one is here which would be amazing! Btw I work remotely & have very flexible days where I can basically pick my own hours (within limits) so I’m planning to work until giving birth. Would love to hear any info anyone has on this!