OK, I read an article that did some calculations on the Epstein drive so I have an idea of how fast the ships can travel.
A 1g burn will have an acceleration of 9.8m/s^2. If you multiply that by time in seconds, you'll get the velocity. There are 86,400 seconds in a day. So after one day at 1g you would be traveling at 846,720m/s. That works out to about 526 miles/s. There are 3600 seconds in an hour so that would be about 1.9 million miles per hour.
The distance fro Mars to Jupiter, on average, is 342 million miles. So you would want to do a 1g burn for half of that distance.
According to the formula I found, distance = 1/2(acceleration * time^2). So t^2 = 2d/a = 2 * (171M miles / 0.0061 miles/sec^2). That works out to 237k seconds or about 2.75 days.
That means that your maximum speed before you start your deceleration would be 1450 miles/sec or 5.2 million miles per hour. That's about 0.78% of the speed of light.