kH/GH have no direct effect on cycling. I wouldn't do anything to alter these water parameters. You might wish to choose fish that have home environments closest to those of your tapwater, though.
Altering properties of your tapwater to suit your tank is a sticky business, because you'll be forever stuck doing that again and again whenever you change or add water. In reality, it's easiest and most convenient (and therefore best for your enjoyment of the hobby) if you minimize this type of management and choose fish that will thrive in your tapwater.