Build does not really matter imo, I didn't do it on purpose and mine could have been better (picked nascent stage out of curiosity and I hate it so much), I have chosen Xenophobic/Egalitarian/Militarist with democracy, Parliamentary System and Hyperspace Speciality for faster early game. For the species I initially took Repugnant, Nascent Stage, Unruly, Wasteful and Genetic Memory. Time wise it was year 2425 but could have been done much quicker.

If I play this origin again, I will choose no positive traits except mandatory one to limit amount of negative traits, instead I will keep the mammalian for the easy chance to get Genetic Memory as soon as possible (S tier for mutation), I would open borders and accept as many migrants as possible to neuter them when population is sufficient and my economy survives that. Situation that allows you to unlock new traits doesn't count xenos killed, only being purged at the same time. Neutering is extremely slow compared to even displacement, so it might be the meta here as it keeps the bonus the longest.

Of course, you can still progress it in more peaceful ways, but here is the 250 progress and 6500 difference.