How Many Miracles are Required to Canonize a Saint?
Saints [Catholic, Orthodox, Open]
SAINTHOOD 101: Rules for Becoming a Saint [Catholic Caucus]
The Process of Becoming a Saint (Canonization) [Catholic Caucus]
Pope Lists Criteria for Causes of Canonization
Here are references for the process for Catholic sainthood.
Although I think in the case of Blessed Mother Teresia of Calcutta, it was a few short years after she had passed on.
Even during the funeral Blessed John Paul II, I remember there were chants for him to be declared a saint. Do you remember that?
An add-on to post 15, the Church did put her on an early fast track, because of the holy life she lived.