Considering that the government cannot even manage to send bullets with the national guard (LA riots), I wouldn't trust them to get vaccines to us within 5 days of exposure.
Best to be prepared - that means get vaccinated ahead of time.
More disturbing are the potential complications from the vaccine. This can include blindness caused by touching the vaccination site when the virus is shedding, then rubbing the eye.
Mortality rates from smallpox (roughly 30%) were estimated in the period prior to widespread antibiotic availability for the common secondary infections.