we start by writing the discrete rate equations. However, the rate equations are highly nonlinear and have so far eluded exact analytical solution except in a few limiting cases. [@cohen; @hong] Hence, we study the kinetics of self-assembly by closing the discrete reaction rate equations by insisting on plausible approximations. This way, we obtain dynamical equations for the first two moments of the polymer length distribution. These are the number of polymers and the polymerised monomeric mass, of which the latter is primarily probed in assembly experiments. [@tuomas_science; @hellstrand; @tuomas_review] We obtain asymptotic analytical solutions of the resulting dynamical equations. From our analytical solutions we quantify the early time kinetics and show that the scaling of the lag time with the total monomer concentration is identical to that of the standard *end evaporation and addition* pathway even in the presence of the proposed *body evaporation and addition*. However, the lag time significantly does decreases with increasing predominance of *body evaporation and addition* pathway. We also show that when only one of the two addition and evaporation pathways is present, the half-time and the apparent growth rate differ in their scaling with the forward rate constants of monomer insertion.

![Schematic showing 