We study microscopic single domains nucleating and growing within the coexistence region of the Isotropic (I) and Nematic (N) phases of a low molecular weight liquid crystal in magnetic field. After rapidly switching on the magnetic field we measure the time needed to align the nuclei of sufficiently large size along the field. We find that this time decreases with the square of the magnetic field. When the field is removed the orientation relaxation time of an aligned domain is observed to be longer. The growth rate of nematic domains at constant temperature is found to follow the predicted power law and to increase with magnetic field.