Thanks for your question. There are quite a few variables here and without more detailed information we can only provide you with a fairly general answer.
Polishing a concrete floor at the minimum typically takes a full day's work. It all depends on how old the concrete slab is, the condition of the original concrete and any surface changes over the history of the floor. For example removing tile glue can require a different approach. Some floors can be polished easily, some require great effort, and some concrete is not suitable for polishing.