You said to start a new pineapple after you harvest your pineapple, When yo start a new pineapple it can often take 18 months to grow adn mature to produce a new one. But if you let it there in the pot or in the ground, which they can take a pretty good freeze without incident so they can be planted as far north as zone9. As soon as the pineapple starts to send up the flower; unseen and below the bottom leaves the next generatrion of plants are already forming. As the fruit grows and matures the new plants begin to grow and usually several of them and the plant multiplies. Is left alone usually the next year not 18 months later there will be another fruit produced. The real benefit of keeping your original plant is that it will be very well established and mature thus producing an even larger fruit, also for every lead you get you will also get a fruit from. I once had 3 pineapples on a single plant at one time. The plant will of course get bigger so if you still want a smaller plant then after it is maturing seperate the plants and this will also give you a perfect looking plant and not one with short ugly brown leaves. If starting new plants is yourgoal then continue to plant your pineapple tops for fruit that is good but never get rid of your healthy established plants they will only further reward you.