“cold” automatic transmission Omega B 2.0 16V

Hello, if I start my Omega which is in the garage after longer service life then the automatic transmission switches up very delayed, that is, the Omega drives very long in the 1st or 2nd gear. If I switch on the winter program, then it switches up. If I have driven so 1-2 km it switches back to normal, so is only when the oil is cold!? Is there possibly too little oil in the gear? Frank