Kelly - this is a bit like asking how long a piece of string is but I'll try and give some guidance from my (limited) experience.
I seem to remember the Behomer Roaster has a 2lb - 2 1/2lbcapacity and the times seem to be roughly 16-20 mins per roast (I haven't used one before, so I'm just going from what I've read). So 20lb would be 2-3 hours of roasting time.
I haven't used a Crankenstein, but cracking doesn't take a long time - 20lb would take me approx 10-15 mins at home using a Champion, so I can't imagine it would take much longer than that . . . maybe half an hour??
Homemade winnower will depend entirely on your design and how efficient it is.
Pre-grinding I don't do but I have seen it done on Youtube videos and it seems fairly quick with a hand-crank device . . . maybe another 30 mins
Spectra . . . this is your swing variable. I've had my chocolate in the machine for as little as 8 hours and as long as 30 hours. Depends on the beans, sugar, milk powders etc you're using and flavour you're aiming for.
Tempering and moulding can be time consuming initially but is something you get quicker at and depends on your setup. I have not used a Little Dipper, but believe it is a melting tank rather than a tempering machine. I hand temper and mould my bars with a Mold Art 6kg melting tankand would take ~2 hours for 20lbs based on my setup. 20lbs is a lot though - if you wanted to do it all in one go you'd need quite a few bar moulds and a large capacity melting tank.
Cleanup also takes time and depends on your setup and how clean you work.
