South Carolina Property Tax - New Exemption?

We are moving to York County, SC this summer and have been told about the new tax structure for property tax. But we have been told different stories and I checked the Tax website and didn't understand the explanation. We have been told that there is going to be a $100K exemption on property tax - when is this going to take place? And, how does the county get the appraised value of a newly purchased house?