I rack on a schedule more determined by convenience than by a strict schedule. It's common to rack at some point after the vigorous primary has completed to prevent too much of that big pile of yeast from autolyzing (dying and breaking down), and that can be done either pretty early while fermentation is still active or later to begin the aging and conditioning period. Some folks like to age "on the lees" and feel that the flavor of a little autolysis is part of an enjoyable mead, and some people militantly (perhaps phobically) rack many times over the mead's life.
Racking certainly introduces some oxygen to the mead; a little can be a good thing to help it finish fermenting, degas, and allow a little bit if that oxidized flavor for complexity. Unfortunately it's tough to gauge how much racking will overdo this, and you do lose some mead with each racking too.
My meads tend to fall clear just fine with only a couple rackings. First at some point after fermentation is done (a month or so) and then later as the rest of the gunk falls out (a few months later). I degas manually by stirring gently.
Does that mean you're into the ferment a couple/three weeks? If so that's normal. The initial ferment is pretty vigirous, then tapers off slowly to finish, hopefully fully fermented out if nutrients are good, yeast are healthy, pH is OK and temp is adequate.
Yet another question. I'm not even to the second racking yet, but this thing has slowed down to where the airlock bubbles about once ever 10 seconds. Is that normal?? The thing is at about 72 degrees consistently.
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in Lyons, CO