The very first place was probably, technically, in Antartica. Antartica was experiencing nearly full daylight at that moment, and there is a location in Antartica that is exactly on the IDL. Besides Antartica, the next place was probably the eastern-most island of Kiribati, called Caroline Island. Kiribati is a nice Island country near French Polynesia.
If you want to learn more, here are several helpful links:


