How long could it take for my hemoglobin level to return to its pre-surgical range if I receive a transfusion? If I didn't?

6-12 weeks. There are a number of variables here. First, how low was your hemoglobin when you started? Second, if you received a transfusion, what was your hemoglobin after? It takes about 90 days to cycle through your blood supply, so after 3 months, you should be back to your baseline.
8=12 weeks. Hemoglobin is carried inside red blood cells which have a lifespan of 120 days. If you loose blood due to surgery for example, your bone marrow will produce more than usual numbers or red cells to compensate the amount lost during procedure. Transfusion of one pint of blood will increase instantly your red cells in 1 gram of hemoglobin or 3% hematocrit.