Says it all in the question really haha. Heater is fitted and switched to 24 degrees - which is the temperature the water needs to reach. However, when i put the water in it was very cold, and even now after 6 hours, it is STILL very cold.

Yeah thanks but.. what is new tank syndrome? I was going to get my fish 48 hours after the tank being set up. That's what it said in the instructions?? Is that wrong?