If you haven't gotten any yet, check out my post for a screenshot on my lowest amount which was about 40WPM on the 20 you hold on Steem Engine.
My highest was 60WPM and with over 100 TPC held, I got 2.02 for the one shot.
So I found getting 50WPM or so will get roughly 1 and a half TPC.

Also 5 times a day and you could be earning 7+ TPC a day, depending on your speed and how much more you buy above the 20 TPC you need.