The Anglo-Australian miner, which wants to use the world's largest fertiliser-maker as its entry into the global food industry, also said it had no plan to change its $130-a-share offer and shrugged off talk of a China-backed rival bid emerging.
Potash said an extension of BHP's offer by a month to 18 November did not change its position and again urged its shareholders to reject the "wholly inadequate" offer.
The offer was extended after Canada's competition regulator sought more information. However, investors said on Tuesday the delay was expected and could work in the miner's favour unless a serious rival offer comes up.
"There was always the impression it was going to be a long-winded process and at this point in time we have not had any competing bids yet," said Peter Chilton, an analyst at Constellation Capital Management, which owns BHP shares.
"To some extent the longer it drags on, it might be better for BHP because it reduces the tension, although if someone else comes in like the Chinese it is another game."
A source familiar with the transaction did not rule out further extensions to the offer period if they were necessary to clear regulatory hurdles. There have been indications from some BHP executives that the deal could drag out as far as Easter.
A company with a takeover offer on the table, however, does not want the proposal to sit for too long, as it not only lengthens the time for a rival bid to emerge but also invites added regulatory red tape and shareholder fatigue.