19th Feb BBC say http://news.bbc.co.uk/sport1/hi/boxing/statistics/default.stm but boxrec hav it TBA http://boxrec.com/list_bouts.php?human_id=325260&cat=boxer
It was the 19th of Feb but has been pushed back to April, probably because of Macklin's cuts/bruises from his last fight. An exact date however hasn't been decided as far as I'm aware.