The bottom line is, we are still in the Quaternary. (No one has presented any real physical evidence to the contrary!) The Quaternary is a geologic age characterized by cyclic continental glacial ice sheets. The last glaciation ended roughly 22,000 years ago. Its coming back, its just a matter of when. There is nothing we can do about it other then do what man did the last time! Migrate to warmer climes!
Years ago I heard the process can start - and have impact - fairly quickly. Ice 'grows' up from frozen land (summers absent for a few years) long before any 'glacial movement' starts... Or is that myth?