The V2 rockets were a strategical weapon, not a tactical one. Accuracy was horrible and they barely managed to hit a target as close and as large as Greater London.

BBC has a map on the rocket hits on London. Note how spread out these are.

Another sign on how inaccurate these rockets were are that one crashed - in Sweden - during testing in June 1944. Swedish authorites gathered the junk and sold it to Britain in return for mobile air search radar stations (that were dated by British standards, but since Sweden had no air search radar was top notch for Sweden).

By the time the V2s were ready, in September 1944, Finland was leaving the war, Romania had been over-run and the Soviet were just outside Warsaw.

See this map for the frontline on the 19th of August and how Romania was over-run.

The only time the Germans tried to use the V2 as a tactical weapon was against the Ludendorff Bridge captured by American forces at Remagen. On the 11th of March 1945 they fired 11 V2 rockets against the brigde. The closest one landed about 500 meters away, while the furthest missed by 64km.

The range of the V2 rocket was only about 320km , which means that by the end of September 1944, there's nothing in the Soviet Union they can hit - the front is further away from Soviet territory - perhaps with the exception of the Kurland pocket, but sending your top technological devices into a surrounded pocket might not be a good idea. And they would be unable to hit anything vital anyway.