"When the Prostitution Reform Act 2003 becomes a law, it starts the next day, except for a few parts that start six months later."
This Act starts on the day after it gets the Royal assent, except for some parts.
You need to know that the Royal assent is when the government agrees to make the Act a law.
The Act will start being a law on the day after that happens.
Some parts of the Act, like Part 3, sections 49, and section 50(2), will start 6 months later.
This means you will have to wait six months for these parts to become law.
These parts will start being law six months after the Act gets the Royal assent.