  Inspired by the pioneering work of Escobedo and Velazquez
\cite{EscobedoVelazquez:2015:FTB,EscobedoVelazquez:2015:OTT}, we prove that
solutions of 4-wave kinetic equations, under very general forms of dispersion
relations, develop condensation at the origin in finite time, under weaker
conditions on the initial data than the ones considered in
\cite{EscobedoVelazquez:2015:FTB,EscobedoVelazquez:2015:OTT}. We also provide
some estimates on the non-condensation times of the solutions.
