Do I have to empty the darlek now?

You use the compost whenever you want to use it, assuming the stuff inside is ready

It's unlikely to rot any more in the bin, but you can leave it til you are ready to use it

I do mine in Spring when I want to use the compost  

I keep mine over winter too. I have a couple of full ones that are cooked but they will sit there til spring. I keep checking them and moving them with my broddling pole  to check that ratty has not set up home. I keep them topped up too - kitchen waste in the ones at home and allotment waste in the plot ones.   I turned out some cooked stuff recently and used it in the area where I was planting garlic, shallots and onions.  I'd rather use it for a purpose than use it willy nilly, as it's too precious