Microstructural changes in epitaxial SrRuO3 films grown on SrTiO3(001) during early stages of growth by pulsed laser deposition were studied mainly using synchrotron x-ray scattering. At a very early stage of growth, the film is composed of a single (110) domain, in contrast to double (110) domains in later stages of growth. This domain evolution appears to be closely linked to a significant enhancement of crystalline ordering in the in-plane direction.