What engine does it have ? 3.6 or 3.8 l Does it have flex fuel ? How long do you work 8 hrs. Sould be cold after that , unless it's hot where you live . Hooking up a scan tool an viewing live data from the coolant temp sensor , could be lying to the PCM/ECM ,does the IAT intake air temp sensor show close to what the coolant temp sensor shows ? The PCM/ECM goes by what the coolant temp sensor says for fuel control ,when it says the engine is cold when it is really hot the computer will supply too much fuel causing a hard or not start problem . Try holding the gas pedal all the way to the floor after work an see if it starts then , holding the pedal to the floor puts the fuel system into clear flood mode , only gives half the fuel . Engine flooded .
Clear Flood Mode
If the engine floods, clear the engine by pressing the accelerator pedal down to the floor and then crank the engine. When the throttle position (TP) sensor is at wide open throttle (WOT), the powertrain control module (PCM) reduces the fuel injector pulse width in order to increase the air to fuel ratio. The PCM holds this injector rate as long as the throttle stays wide open and the engine speed is below a predetermined RPM. If the throttle is not held wide open, the PCM returns to the starting mode.

Hooking up a scan tool an viewing live data is still best way to diagnose , not guessing an cleaning parts .

The Scottie Kilmer video channel on YouTube did a video on this a few days ago. He puts out two a day!

In the one, he described what you are experiencing. When you start the car from cold, it requires the electronic choke to deliver a richer mixture. In your case that richer mixture is flooding the engine. Clean the Mass Air Flow sensor and throttle body with MAF or Throttle Body cleaner. One thing you can try is flooring the gas pedal when you try to start, he said it does something, adds more air and less gas? As soon as it catches, you flutter the gas pedal.

I have now owned this Buick for 3+ years and have put 75k miles on her. She is still very docile, quiet and well mannered, just what you would expect from a Buick.