We may well see price changes sooner than I had first believed. Today's news shows not only a very strong $C but also indications are that the US Federal Reserve is planning to lower interest rates in the near future. Yesterday's US jobless report was, plain and simple, terrifying for American economists (over 300,000 jobs lost) and may be signalling a recession is looming south of the border.
Should the US Fed lower rates 0.25% as many believe it will, that will trigger an even greater appreciation of the $C that week. Stay tuned; the Fed is expected to act sometime in the next 1~3 weeks.
Should currency valuations go much above the 4~5% range, I would expect a much quicker trigger of price adjustment than the 2-3 month window it would take if they hover at or below that level.
Besides the hassle (price adjustment isn't trivial) normally a business will try to create a bit of a war chest to help cover a mistake should the currency tank after a rise. But indicators are that the currency change is going to stick (eg the US dollar is falling against all world currencies, and the $C is far from the trade-weighted or price-parity level of about $US 0.80).