I believe the answer to your question would be when the big supermarkets accept some form of btc for their goods.
Yes, I reall ywonder what will be the point where supermarkets start accepting it though. Right now it seems like internet shops and bars/restaurants accept it, but not much more than that.
What's next after that?
Where in line do supermarkets stand?
People will use bitcoin when the following conditions are met:
1) Apps make it VERY easy to buy/sell and trade
2) Big stores and grocery stores accept it, IE Target, Walmart, Food 4 Less, Stater Bros etc
3) Stores offer discounts for using bitcoins (pass on some of the savings from credit card percentage charges to us)
4) People can take part of the their income in bitcoin (see
https://bitpay.com/bitcoin-payroll-api)
1)
coinkite has bitcoin debit-cards, maybe not thé killer app everyone is waiting for, but a step in the right direction
2) agreed, but i don't know what would trigger this event to happen
3) often happens, but they have to accept it first.
4) already happened