I think you should start as fast as possible with Jalapeno, because as difficulty raises value of the block goes down. Currently you receive 50$ per block, in the near future you will get $25...
It's
BTC50 and
BTC25, and it's unrelated to the difficulty.
In the first few days of the ASIC being out they can be quite profitable, but the difficulty will quickly increase to diminish the profits. And if you preorder now you're taking a risk with respect to the delivery time. Read up on all the information available and then decide if you want to make this investment. There's no free lunch, and there's no sustainable way to quadruple your wealth every month.