I'm currently in an elliptic Laythe orbit (Pe: 117km, Ap: 3,168km) and I have 4k dV left. I'm having trouble plotting a course back to Kerbin. I'm trying to escape when Laythe is moving Jool retrograde to get an extra boost, but I can't get my escape trajectory to be Jool retrograde. When should I burn when returning from Laythe to Kerbin?