Query regarding CBC. Correct diagnosis?

I had fever 02 days back and my doctor prescribed me antibiotic and paracetamol on the first day of fever and ordered me to get a CBC test done 3 days after consumption of medicines. He stated that it to be a viral infection but even then he prescribed me antibiotics. Now the question arises that if after consuming antibiotic for 03 days I go for a CBC test, will bacterial infection be detected? As TLC might be in normal range now, after 03 day consumption on antibiotics or is my doctor advicing me the correct approach towards the test . Because what I know is that CBC is ordered before prescribing antibiotics but my doctor prescribed me antibiotics first and then said to get a CBC done after 03 days. What if the CBC now comes normal ? Will he able to form a correct diagnosis ?