In a footnote in this document it states,
Iggerot Moshe, Orach Chaim 4:60. Rabbi Feinstein writes that use of
timers to automatically regulate machines to perform work forbidden to
Jews on Shabbat is generally forbidden, with the exception of turning
lights on and off. He believes that use of timers would severely
disrupt the Shabbat atmosphere, since all of one's work could be
performed by machines. Rabbi Feinstein asserts that just as the Sages
did not want, and therefore forbade, our asking non-Jews to perform
work on our behalf on Shabbat for fear that this would disrupt the
Shabbat atmosphere (see Rambam Hilchot Shabbat 6:1), so too the Sages
would not want machines to do work on our behalf during Shabbat. Rabbi
Feinstein appears to be the lone authority to adopt this approach.
It seems that if you want to follow Rabbi Feinstein then you should not set the timer to brew the coffee for 8:00 Shabbos morning.