Like Soly said, usually you should just have a few (I go up to about 8), but make sure it takes no more then one turn to get the troops made to a port (Shinano to Totomi, Yamashiro to Wakasa etc...) I usually have one province for Archers (Totomi if I can get it) Yaris (Armouries are nice since you can build Naggy there too) Cav (Shinano) and Monks (home, or Kii or Kaga (?) if I can get them early enough). Remember ports are a shoguns best friend too.