The word Prestimony does not currently appear in any reputable English language dictionaries. However, based on its spelling, we can assume that it is pronounced /prɛstɪmoʊni/. This is because the prefix "pre-" (meaning before) is often pronounced as /prɛ/ in English, followed by the vowel sound /ɪ/ and the syllable "-mo-" is pronounced as /moʊ/. The final syllable "-ny" is pronounced as /ni/. The meaning of this word is unknown.
An annuity paid to a priest for saying prayers at certain stated hours.
Etymological and pronouncing dictionary of the English language. By Stormonth, James, Phelp, P. H. Published 1874.