I thought of that once...
In a story I started without any more than premise and scene (i.e., no plot, so no clear idea of where to go with it...).
They sent space probes first -- back in time, and with an approximaly correct position and vector. The autonomous probes had propulsion, maneuvering, and on-board navigation algorithms to find the target (Earth) and establish orbit. Getting onto the surface without materializing inside it was a lot easier that way.
My character was an archaeoastronomer, who worked on the software the probes used to recognize where and when they were, by relative star positions back-extrapolated from known proper motions.