Where to set timing

I'm going for basic timing. Just tuning it up and just trying to be sure about my timing. I have no rpm gauge. I put a slant 6 with a 3 speed on the colunm that i moved to the floor in a 53 dodge pickup I have. The slant is out of a 1978 dodge d100. My marks go from 0-20 mine was originally at around 6. I have a timing light. I'll watch the video and go from there haven't been on in a while. Thanks for the help guys