In that sense, the time is right: the impact of QE is being felt just as the recovery is being confirmed, and it will reinforce it. It’s a mechanism that is potentially powerful.
The final channel, of course, is the exchange rate: this is not an objective in itself, but it reflects market participants’ expectations of the different monetary policies being pursued on each side of the Atlantic. If you include the oil price too, you have a combination of factors favouring recovery and investment.