I would think it's the classic UK zoo plan of aim for the schools' Easter break, then worst-case if it's a bit late it's ready for the summer holidays.
I am really impressed with this new Chester Zoo map and it is so much easier to look at compared to the former cartoony style over the past 10 or so years. I can't wait to see this map again when Heart of Africa is complete next year.
I have noticed the Philippines Spotted Deer are not on this map in their new enclosure, also none of the monkeys that are opposite the Camel/Onager enclosure.