While that is generally the advice, in my experience you're much better off treating them somewhat carelessly. The main thing is to not clean them too much, and to not let them stay wet. The seasoning happens with regular use. With a new pan you want to let it stay on the heat a bit after use so the oil has some time to stick to the pan properly. After the third or fourth time using it it should start getting pretty anti-stick, until then just use a metal spatula to dig stuff out of the pan.