You are correct about the March 9th deadline which is just a guess that happens to be wrong.
I say that because Jason Napodano, an equity research analyst who follows InVivo for Zacks Investment Research commented on that article as follows:
"The company tells me the HUD guidelines issued on January 24, "Did not reset the clock." I asked if they have received a request for additional information from OOPD, but management would not comment. They said it is their policy to not comment on interactions with the FDA / etc..."