The tanker leg on which he does the orbit, is the leg in between the waypoints 1 & 2 for that track.
So, for example Pegasus.1 and Pegasus.2. If you look it up in GE for Pegasus, the distance of 1 leg is 15 miles.
What works best for me to RV with the tanker, is to fly to the IP (Pegasus.IP), and from there to Pegasus.1 and after that Pegasus.2.
If the tanker is on the other leg, I wait until he's 45 degrees on my left nose, he will be about 10 miles from me there, and start a 30 degree bank turn tot the left. That mostly gives me a pretty good rejoin.
If I'm trailing him, I wait until he gets in the turn and take a lead turn on him, resulting in a pretty fast rejoin. Or if I'm trailing him by a good distance, wait until the gets on the other leg after his turn, and repeat the first scenario.
Sometimes you have the scenario where he is in the turn towards the .1 waypoint, when he arrives there. There I do a 360 turn to get behind him, mostly resulting in getting too far behind him. This case is mostly the ugliest rejoin.