you can get a panzer4 or t34 at around around 9-11 minutes depending on when and how many caches you build. this is a huge opportunity to punish players that are saving for call ins and to completely push them off the map and kill their infantry in their base.
Players have proved many times that few mines and a pair of AT guns+maybe some infantry AT squad is enough to hold off meds until heavies arrive, this is especially easy for axis which have superior AT and are fighting weaker armor, pretty much only sherman on allied side is truly effective medium.