I don't think so, but it can be a pain when you do go to register your business later on. From personal experience, I started advertising with my business name prior to registering it with NS Joint Stocks, I did however, register my name with CRA. The problem was that when I went to register my name in NS, another business had a name that was similar to mine so I had to work with NS Joint Stocks to get my name which took a few weeks to sort out.
So in the end IMO the answer is no, as long as you have done some research to see if anyone else is using the business name. However, from personal experience I would wait the two days and 'hold' a business name to avoid the difficulty that I had.
Brian