i mean i cant speak for the first time with em... i cant start working there...I guess you are stuck when washing the dishes? After you start to wash, you can click on Ashley or Joe. Don't use the "talk", but "eyes" button. Then Ashley or Joe (depends on which one you clicked) comes to Monica and gropes her. This will increase your lvl with them. Lvl 2 is max. progress so far.
When both(!) are on lvl 2, Monica can start to work as a waitress. When you steal the tips, you can unlock 4 scenes with Joe and 3 with Ashley and start the dance scenes on the pole.