I think you would be able to sit under the new syllabus as this starts from the 1st January 2019. The year to pass is only for students who have already started studying the existing syllabus.
I contacted ICB as I have already started self-studying Level IV but wasn't sure if I could complete it within the 12 months as, due to other business commitments I can't study over the summer period.
The suggestion was that the change of syllabus is more when subjects are covered rather than a big change in material i.e. more concentration on digital bookkeeping.