You're finding conflicting information because there are so many different types. Of those most cold hardy and reliably perennial, some are warm/cold/cool germinators and would benefit from sown approximately 70F for 2-4 weeks, move to 35-40F for 4-6 weeks, then to 50ishF for germination.

Germination can be improved in others by a 90 day moist chill, and the types grown as annuals can be sown warm with no pretreatment. Are these purchased or traded seeds, if traded, can you find out which aristolochia...