If you're solotop and you followed my tips to get the minions under your own turret, you can farm in safety. Sometimes the wave pushes away from the turret a little bit. Basically you can trade waves with Jax. You get one under the turret, they push forward, and he gets one outside turret range. But when you keep Jax this close to your turret, he's very far from his own turret.
So if you're just trading waves with Jax at this point, you're still at an advantage. You're basically impossible to gank (until the enemy is ready to turret dive) and Jax ends up being a really easy gank as long as you and your jungler are coordinated.
Don't rush your jungle and don't start griping because you don't get an immediate gank, but let him know Jax is overextended and easily ganked. At champion select, make sure to take Exhaust, particularly if the jungler on your team doesn't have a good CC, as Fiora has no real CC. Then just make sure you and your jungler are on the same page for the gank. Engage at the same time and get the kill.
Assuming you successfully get a kill, remember that Jax (or whoever is in your lane against you) has been successfully harassing you. You still need to keep the minions under your tower. So you have two options really, either go back to your tower and continue to just last-hit minions under your tower (keeping the wave frozen under your tower), OR kill a wave or two and then leave the lane for a bit. Whether you're going back to base to spend or you're going to gank mid-lane. I think it's never a bad idea to help the jungle set up a 3v1 gank mid after he's just fed you a kill (or assist) in top lane.