A new formula for the dynamic spin susceptibility has been analyzed with taking into account the strong electron correlations. The correlations sufficiently modify the Stoner-like factor and as a consequence change the phase diagram of the instability. It is remarkable to note that the instability area moves to the low doping. The possible approximates (lorentzian and gaussian) of the real part of the spin susceptibility have been considered. The behavior of the correlation length with doping and temperature in both cases is discussed.