Education Minister Jeff Johnson says it will take that long to write regulations to support the changes and to give school boards time to make their policies conform.
The act gives school principals and trustees more authority to clamp down on bullying — not only on school grounds, but also off-site or on websites.
Students who can now drop out at age 16 will have to stay in school until 17.
They will also be allowed to stay in school to finish courses up to the age of 21 — up from 19 — without having to pay themselves.
The NDP has criticized the bill and says it should make clear that schools must adhere to human rights laws.