there is no reason to worry about rushing with sand, you put it in your tank when you start to get the cycle going faster and its less of a hassle to worrie about it AFTER you cycle and have spikes, if its from another reef tank, thats one thing, but if you got it out of a bag, there is no reason to leave it untill cycle is done or almost done, we did CC in our first tank, then had to remove it after 2 months, HUGE spikes when we put differnt sand in, had to recycle the whole tank and lost some of our fish. taking it slow is best thing, but that has nothing to do with sand, i would put it in over the dead stuff now and get it going, good luck with your first tank and welcome to the board.