How Long I Have To Wait After My Last Cigarette To Had A Blood Test?

The insurance companies do not measure nicotine in the blood. Instead they measure COTININE in the urine.
Cotinine is a metabolite of nicotine. It has a much longer half-life than nicotine. The half-life of cotinine is 24 - 36 hours.
For a regular smoker it takes 10 - 14 days for the cotinine concentration in the urine to fall below detection levels.

How long after I quit smoking should I wait to take a blood test to check my CEA levels against the tests I had taken as a smoker?

Nicotine will stay in your blood for only 1-2 days.