⟨Kerbinator(no guarantee suggest)⟩ Mechjeb works quite well in deciding a window
(need to have patched conics on and select target celestial on; must not have a flight plan or the node will have been erased by principia instantly)
-------------
MJ window is at 173d 16h costing 2660dv; Principia cost 100 less
burn last for 27d2h, window at 157d4h, burn medium is at 170d18h, a bit earlier
(I'm doing a Earth transfer hohmann with 2N ion thruster, to get the accuracy proved)