It seems you submitted sponsorship May 2011 and application received on May 9, 2011. Next? It will take normal processing time and CIC canada will request more documents when needed, if everything ok they will transfer to visa office of your parents and it will take another normal processing time. Next stage VO either request medical and other supporting documents before passport or request both. What happened to me requested both. Final stage dm. That what I know.
My application submitted 2009 and so many delays like principal applicant past away due to accident, dependent children gave birth and now PA will take sputum test.
Ppr and other documents may 15
Meds done may 30
Sputum june 4-5-6.
Andy