Well, knowing how they tend to release the characters, by my estimates, the girl we'll call "Nag" is going to most likely be released on December 20th, 2018, while the character called "Cri" (who may or may not be Christie, and I suspect it's transcribed "Cri" because of Japanese phonetics, as there's no "Ch" in Japanese, just "Ku".) is probably going to be released on March 14, 2018. Knowing this, and assuming "Cri" is "Christie", I think we can set up a time table:
*June 7, 2019: New Westerner
*August 29, 2019: New Japanese/Asian
*November 21, 2019: Cut character
*February 13, 2020: New Westerner
*May 7, 2020: New Japanese/Asian
*July 30, 2020: Cut character
*October 22, 2020: New Westerner
*January 14, 2021: New Japanese/Asian
*April 8, 2021: Cut character
*July 1, 2021: New Westerner
*September 30, 2021: New Japanese/Asian
*December 23, 2021: Cut character
After that, who knows what the pattern will be, since they've included all the cut characters they can.