At 20% difficulty increase, your ASIC deivce will earn 5x its income of the first difficulty period (total income in those 12 days) during its life time. A jupiter will make 16 coins in the first period if it is delivered in the beginning of October, and 80 coins during its life span, that's the cost when you purchased it
The storm is coming

The simulation on
http://mining.thegenesisblock.com/ shows it earn around 50 coins if it is operational on the beginning of Nov. And halving the coin every 2 months.
What number you plug in for the difficulty?
I don't know what should I input since they use month as a period count, each difficulty period is about 12 days, one month have 2.5 period, but you never change the difficulty between the adjustment. Anyway, the reward is cut by half after 3 times 20% difficulty increase, and for 5 times such increase( 2 months), reward will be cut by 67%. In four month, reward will be 1/10 of the first period, anything after that can be ignored
P.S. I just tested, that page has an error for the first month income, it does not reduce the income for the second and third period in the first month, so the first month income is all based on the first period difficulty, from second month it is about 20% increase per period (monthly increase of 43%)