go off half-cocked: o que isso significa?

A few weeks ago, I went shopping for a new smartphone. I didn't have in mind what model I wanted specifically and thought I would make a good choice just by going from store to store weighing the pros and cons. Turned out I got a cellphone that at the time looked to suit pretty good my needs, but would turn into a big disappointment in the end.

That's because when I got home on the same day and decided to search on the internet for smartphones in the same price range, I found out there was a much better smartphone for me at the exact same price. I couldn't believe what I had just done. Here's what I thought to myself: I shouldn't have gone off half-cocked and bought the first smartphone I thought was the best for me. I should have searched first.

Again: I shouldn't have gone off half-cocked. What does that mean? When you go off half-cocked, you go into action too early without thinking. That expression alludes to the idea of a matchlock gun firing prematurely, before the trigger was pulled. So that was the first thing that came to my mind when I thought of the last thing I did without knowing all the facts. What about you? When was the last time you went off half-cocked?