I got my PR 09/07/2011, I left canada on 21/07/2011, during my absence I had a child born outside of Canada 27/02/2012. can I go back to Canada and make the sponsorship?
You HAVE to start before then because after that you will not be in compliance with the Residency Obligations. You have been outside Canada for nearly three continuous years. If you try to sponsor when you don't meet the RO, you risk losing your own PR status.
Just read the many, many, threads in this section about this.