Extensive two-dimensional Brownian Dynamic simulations are used to determine the effect of non-periodic shear in the crystal nucleation kinetics of charge stabilised (Yukawa repulsive) colloids, and attractive colloids (polymer-depletion driven colloids). Results show that in both systems small amounts of shear can speed-up the crystallisation process and even enhance the quality of the crystal. Insight about the crystal state enhancement (destruction) at low (high) shear rates is provided in terms of the dual nature of shear: shear tends to separate particles that form a nucleus, but at the same time induces an extra flux of matter that increases the frequency of collisions with the nucleus that speed up the process of aggregation. In addition to the analysis of the crystal nucleation phenomena, a characterisation of the transport properties and the steady state as a function of the shear is performed.