get ahead of oneself

verb3

1. •
   To focus excessively on one's plans or on prospective future events without paying adequate attention to the present.

   • Montgomerie suspected he was getting ahead of himself. "I think I am thinking about next week too much," he said. — 1997
2. •
   To develop an opinion based on insufficient information or to take action prematurely.

   • “Frankly,” he said in a moment, “I think the chief constable has got ahead of himself on this one. There's no real evidence the man was murdered.” — 2007
3. •
   To speak or write in a manner in which one makes points out of logical or chronological sequence.

   • She talked so excitedly that she got ahead of herself and looked bewildered and cried out, "What was I saying?" — 1951