The occurrence of low frequency instabilities in a plasma can be due to the presence of a high density of grown dust particles. These instabilities are characterized by analyzing the discharge current, evidencing the existence of successive phases marked by distinct frequency evolutions. The main characteristics of these phases are determined as a function of the gas pressure. Particular attention is paid to the changes of the instability appearance time, duration and frequencies. These parameters seem to be related to global amount of grown dust particles. The instability appearance time is the first parameter that can be easily measured during an experiment and all the other parameters can be estimated from this simple measurement.