That's not that late, I sent out secondaries (7 total) up through October with my first one going out the 2nd week of September or so. First interview was 3rd week of September, second one was last week of January (invite came late November), third one was first week of March (invite was in early January). One thing that I realized was that getting those late interviews often meant having to schedule interviews a few months away. The last two interviews were from the last two secondaries that I sent out. One was submitted in early October, the other was submitted late October.
I can't say applying late really hurt me for any of those schools. I got an interview on the 2nd week of interviews at the first school (and proceeded to bomb it), the 2nd school made non-rolling decisions (so it didn't really matter when I interviewed) and I got into the 3rd one despite not interviewing until March (not to mention not being complete until late November).
I do wonder though if sending in secondaries late kept me from getting interviews at other places where I could've been competitive but like to do early interviews and seem to take a lot of students early like Pitt or Case Western. I got placed on hold at both places after I was complete and wondered if those holds would have been invites if I had submitted a month earlier. It's all hypothetical though, I applied late because I took my MCAT late, and if I had taken the MCAT earlier, I probably wouldn't have done as well as I did.
