Leave it for now. They acknowledge when they actually assign to readers. In one of my submissions that was two and a half weeks later.
On a related note:
how long is it usually between the editor saying "we're accepting your story" and the contract arriving?
A few days ago I got a response of "we want to buy your story, contract to follow", and the contract hasn't followed yet. At what point should I email and ask what's up?
Anyone submit to the Australian magazine Aurealis? I have previously over a year ago, and both times got an acknowledgment of the submission within a day or so. This time, nothing, it's been about two weeks. But it says nothing on the website about sending an acknowledgment of submission received. So do I just leave it?