If i am exposed to covid and become infected, what is the soonest that i can become contagious, i.e. 24 hrs, 2 days, or ??

You had been shedding the virus 3-5 days during the incubation period before you even had the symptoms (i.e. people can transmit disease during the incubation period and that's why we do the contact tracing). After you have symptoms, you may become contagious for 2 weeks but most of the time you're no longer the source after 7 days after the initial onset of symptoms.

Agree with Dr. He. You can transmit infection 2-3 days before developing any symptoms. Get Covid vaccine, if you are vaccinated, get booster.