Well done ! That’s the right answer.
To jump the gun means to do something before it should be done.
If someone running in a race jumps the gun, they start running before the gun has been fired to start the race.
French translation
agir prématurément, brûler les étapes
...................................................
Examples in context
’The problems aren’t likely to stop here. Horst says there are "indications" of more errors. But he doesn’t want to jump the gun with any announcements before his internal "reconciliation" review is completed.’
The Republic Online, 15 April 2012
............
’Lewis Hamilton jumps the gun over Jenson Button’s Twitter disrespect
Lewis Hamilton has been forced to apologise after taking a leaf out of Catherine Tate’s book and accusing his McLaren team-mate Jenson Button of disrespecting him on Twitter.
Hamilton, who is leaving McLaren for Mercedes at the end of the year, was taking his cue from a tweet by a journalist suggesting Button had unfollowed him on the social networking site. It led Hamilton to criticise the 2009 world champion.’
guardian.co.uk, 8 Oct. 2012
...................................................
Everyday usage
He shouted at me before I had time to explain, but later he apologised for jumping the gun.
I don’t want to jump the gun but I think we may have a winner here.