How much RSO would I need if I take 100 mg edibles?

I usually eat 100 mg to get a decent high for 2 to 3 hours. How much RSO should I take for similar results?

I know everyone says start with a rice sized amount, but I hate waiting for the high to kick in only to find out it wasn't enough and have to take more and wait more then take more and wait more etc. I'd rather work backwards and go from absolutely destroyed to finding what works, but...i got things where I can't be out of commission for a full day.

Anyways any advice would be nice like: 3 rice sized drops are similar to 100 mg. I know it's incredibly varied person to person and between products, but any advice for those who use rso would be welcome.