[prior to] prep (1714): in advance of: before usage Sometimes termed pompous or affected, prior to is a synonym of before that most often appears in rather formal contexts, such as the annual reports of corporations. It may occas. emphasize the notion of anticipation "if page makeup decisions are verified and approved prior to typesetting, proofreading of pages afterward becomes unnecessary --Publishers Weekly". It is also used sometimes in less formal contexts "they have taught her how to walk (which I thought she did rather well prior to the expenditure of the 200 bucks) --Groucho Marx (letter)".
PRIOR TO
Meaning of PRIOR TO in English
Merriam-Webster English vocab. Английский словарь Merriam Webster. 2012