How Long Before Blood Test Should Smoking Be Quit To Not Show Nicotine?

I have to have complete shoulder replacement. My Doctor will not do surgery if nicotine shows up in my blood test. How long before I have blood test do I need to quit smoking? He will specifically test for it. I have smoked @ least a pack a day for 44 years. I Have been using an electronic cigarette to cut my smoking down,which I have. Thank you for helping me with this question.My age is 57,my height is 5ft5in,my weight is 185lbs. Have bi-polar, depression,panic attacks,post traumatic stress disorder, complete hip replacement,severe trauma to head after being backed over & ran over with car, punctured lung,both arms go to sleep from shoulders to finger tips, sit straight up in middle of night feeling like knives stabbing my finger tips with both arms asleep,nerves in neck pinched thin between C2 to T4,neck is separated with nerves intwined from fractured neck i didn't know I had. The accident was July2007. Need surgery on neck also,no cartlidge in one shoulder,very short term memory loss,equilibrium off when walking with lots of people around,no strength in right arm since accident.