We will be visiting my family in Szczecin for a few days, but after that we want to see Krakow, then Lublin (Bilgoraj) and return to Warsaw.
Last year we drove from Krakow to Wolin which is above Szczecin on the map. The whole journey took us 9 hours. We set off at 4 am when the traffic was little. We took the highway from Krakow to Legnica near Wrocław, then headed straight to the north to Szczecin. There were a few breaks to fill in auto gas and straighten the legs.
We need to subtract some time from my 9 hour ride because we went farther than Szczecin destination. But taking into consideration that you are not a driver accustomed to Polish style of driving (which is seen as aggressive by foreign drivers), I estimate you will cover the route Szczecin - Krakow from 10 to 12 hours if it is in the morning with low traffic.
PS. The route is very simple, you can`t get lost, just driving straight ahead on international roads, that`s all. I was also concerned but later didn`t regret.
PS2. We were going on holiday to the Polish seaside last year.
PS3. The highway Krakow- Wrocław is a fast connection but beyond it you will lose a lot of time driving through towns and villages which don`t have by-passes.