Wiktionary
get ahead of oneself
vb. 1 (context idiomatic English) To focus excessively on one's plans or on prospective future events without paying adequate attention to the present. 2 (context idiomatic English) To develop an opinion based on insufficient information or to take action prematurely. 3 (context idiomatic English) To speak or write in a manner in which one makes points out of logical or chronological sequence.