All the Coopers kits I've done have been fine and leaving it for 3 weeks will work to your advantage. Bottling after 6-7 days gives you very yeasty beer usually and a fair amout of losses from the sediment at the bottom of the bottles.
Never tried the wheat beer kit myself, as it is not widely available on cheap offers!
3 weeks is fine like many said its actually done a bit of aging and conditioning probably so you're good to go..
Now you know what to look for on your next brew , obvioulsy try to interferre with them as little as you can, I know it is your first one and I was the same. I still struggle now not having sneaky peaks :