Chicago style does NOT require the access date in citations of formally published online sources. However, if your discipline (or professor) prefers that this information is included, please include it prior to the DOI/URL. Separate it from the rest of the citation using commas for Notes (e.g., ... , access December 4, 2017, ...) and periods in the Bibliography entry (e.g., . Accessed December 4, 2017. ...).