In any case, Harry can pass the test without breaking any laws of Time if he can find someone else with a time-turner.
I expect he may bypass the test a different way. I could be wrong about the timeline, but it seems to me that McGonagall's patronus is about to show up in the warehouse where Harry and Quirrell are having their little chat...
Could be. But another possibility is the McGonagall's patronus passes the message to the Harry that she expects to reach, but then, after visiting McGonagall and receiving her message, Harry dispatches his own patronus to pass a message to the warehouse. From there the message passes to Mary's room, and from there to Flitwick as an errand run on the on the way to Azkaban.
Need send a message to the past? Don't have enough charge in your time-turner? No problem. Just find someone who has already traveled back (using a fresh time-turner) and ask them to carry the message for you.
- This thread has run its course. You will find newer threads in the discussion section.
Another discussion thread - the fourth - has reached the (arbitrary?) 500 comments threshold, so it's time for a new thread for Eliezer Yudkowsky's widely-praised Harry Potter fanfic.
Most of the paratext and fan-made resources are listed on Mr. LessWrong's author page. There is also AdeleneDawner's collection of most of the previously-published Author's Notes.
Older threads: one, two, three, four. By tag.
Newer threads are in the Discussion section, starting from Part 6.
Spoiler policy as suggested by Unnamed and approved by Eliezer, me, and at least three other upmodders:
It would also be quite sensible and welcome to continue the practice of declaring at the top of your post which chapters you are about to discuss, especially for newly-published ones, so that people who haven't yet seen them can stop reading in time.