It's marketing timing, which is usually a silly move to make, but in this case, I just can't help myself so I'm waiting a bit before buying in right now to get a bargain.
The only thing to remember is not to use money you're depending on from an emergency fund or the like. I'm using money that I intended to be invested, so I'm not hurting myself by waiting a week or so to see what happens, other than the week or so loss/gain that I'll miss out on while trying to decide when to jump in with this amount.
No one knows how low it could go or when the market will go up or down, so you're really just counting on a lucky break at this point... which is again, silly. (and I am absolutely calling myself silly for doing this, and I'm not going to make a habit of this at all)