Hi Liam,
if you did it online it's usually up to 48 hours.
If you did it over the phone it's usually immediately. Try rebooting, if that doesn't work you can try searching for missing channels
Help & Settings > Help > TV Care > Missing Channels. Let it perform that for about 15-20min, and then restart your box
Dave
The Service you do for others is the rent you pay for your room here on Earth - Muhammad Ali