Championship leader Sébastien Chardonnet is second, with Keith Cronin completing the provisional podium in third.
Gilbert was the revelation of the opening day. The man from the Vosges region best adapting his pace to the varied amounts of grip available on the damp roads.
“I really enjoyed it and the DS3 R3 was perfect,” said Gilbert. “We pushed when the conditions were suitable, but we had to take it easier in the trickier sections. All of which means we end the day in the lead, which we’re really pleased about.
“We also know there is still a long way to go in the rally and that the rain can make a big difference. It is up to us now to play our cards right to hang onto the lead.”
Chardonnet wasn’t entirely satisfied with his day. He bemoaned a poor tyre choice and admitted that his team-mate had dominated proceedings. However, with a 27 point advantage in the championship, Chardonnet in on course to take the title this weekend if the top three remains the same.
Cronin is 35.9sec behind Chardonnet after being held up by a car setting off ahead of him on SS1, and then several minor errors on Friday morning. A more consistent performance on the second loop enabled him to consolidate his position.
Christian Riedemann, who damaged his car’s rear suspension on SS1, and Enrique Garcia Ojeda round off the top five.
Early front-runner Stéphane Consani was excluded from the rally, and the whole championship, after he confessed to carrying out an illegal reconnaissance of the route. Event officials caught the Frenchman driving part of Stage 4/7 last month.