Elon Musk announced on a previous conference call that he had approved the final prototype of the Model Y for production. Considering the fact that we haven’t even seen the vehicle yet through an unveiling, we can expect the version on display to reflect the production vehicle quite closely. Production is still planned to begin in 2020 and the new Gigafactory 3 being built in China will be the source of Model Y production for the Chinese market.
Gigafactory 3 is a 210 acre plot and construction there has already began work. There doesn’t seem to be any information about production sites for other markets however that information should roll-out over the next several months.