The time profiles of the solar microwave emission exhibit various phenomona reflecting the evolution of magnetic flux tubes before and during the onset of flare events. Different scenarios are posslble to describe the processes of energy release in a flux tube and the interaction of a number of tubes during the preflare stage and the early flare development, Multi-peak structures at quite
different time scales displayed by flux records at mm-, cm-, and dm-waves are examined; they rise the question how to distinguish between repeated energy release at one site and the propagation of the flare disturbances over an extended source area, A discussion of observed time scales and released energy in the frame of some scenarios is carried out.