No no no noooooo! You do NOT soak modern cloth nappies. It will degrade the PUL (waterproof layer) and elastic. You can buy liners - either fleece ones to wash or disposable ones. Breastfed poo washes off very easily though so I didn't bother with liners until my son was on solids.
I would rinse off the poo into the laundry sink or scrape off most into the toilet then pop into a nappy bucket until wash day. Do not use Napisan, just use 1/4 the amount of regular detergent and a long cold or warm wash. I haven't bothered with a nappy sprayer but it certainly makes the job easier!