Typically Zillow will refresh Smith & Associates feed every day at 5am EST. So shortly after 5am EST their listings will update photos/information.
If there has been update that has not been reflected on the Zillow site after 5am, the best approach will be to email brokersupport@zillow.com.
In the subject: MLS# - Address
In the body leave a brief message letting them know what the issue is, their response rate is pretty quick.
Example
