<p>Harvard, like most colleges, does have a system for logging school reports, teacher recs, etc. that arrive before the main application and then marrying them up with the application when/if it arrives.</p>
<p>That said, it is MUCH easier for them if the application arrives first (and this also reduces the chance of anything getting messed up). The application instructions on the website strongly encourage students to get the application in as soon as possible - they even let you submit your application without the essay, which you can then send by hard copy later. (My son did it that way and was still admitted, so they don't hold it against you.)</p>
<p>Bottom line, if at all possible, it's a very good idea to get the application in before the other pieces start arriving.</p>