Okay, so, for the whole week I've been into Bitcoin, I have studied it for at least 10 hours cumulatively. And I have decided that I really want to mine. So I have a few questions.
1. I know that the difficulty will be going up once Cointerra produces its machines. But should I pre-order a 2TH/s machine or get into now?
2. If you think I should get into it ASAP, then should I just buy 300 USB ASIC miners or should I buy something else available right now?
IMO neither is really an answer. If you get into it now, the only decent miner you can get is pretty much the Block Erupter Blade, of which if you get hold of the old models, can hash at 13GH/s, otherwise 10.7GH/s for the new models. They don't have a particularly spectacular GH/$ nor GH/W as compared to the CoinTerra but they are an option if you must start now. It is worth noting though that they might not ROI, due to their relatively high cost per GH.
For the CoinTerra, no one can really predict. It definitely is much cheaper in terms of GH/$ and GH/W but I personally suspect that it won't necessarily ROI, or rather, maybe just barely break even. No one can predict bitcoin difficulty sadly, and it might really hit the parabolic of an e^x curve at that point of time, making the CoinTerra useless. Of course this is just my speculation and personal thoughts but it is possible that such a scenario might play out.
Since you really want to mine, I suggest you do it on more of a 'for fun' basis as compared to 'for profit'. The latter mightn't work out at all.