Rubbish.

If your in the US a core part of achieving the patent often requires you actually selling the product for a period of time (or demonstrate selling it). Patents take an AGE to process so he's right you do need to be considering an application fairly soon; but if you stop pushing your sales forward and another company happens to start selling the same tech first THEY have a right to the patent too - and you might have a fight :)

Sell first, patent right after. Profit.

(if your not in the US - thr UK for example - things might be a bit different, you can get a patent a little more easily here)