If you are using the latest FMGS then you also get the opportunity to define the angle with which you would like to intercept the offset. We only got this function last week and its a big improvement on the standard 30 Deg. which tended to involve a fairly energetic bank angle. FMS2 Rev 1.a has lots of new and handy tricks up its sleeve.
"Rev 1A includes additional options for the lateral offset function. The offset can now be
defined by a Start Waypoint, End Waypoint, Intercept Angle and an Offset distance. "