Yesterday I told you to not bother an editor/agent about the progress of your manuscript in the slush system. However, if you haven't heard from them within their stated response time (for me three months), you can follow up.
Keep in mind though, that you need to be polite and nonobtursive. Remember to not make demands or accuse the editor of laziness or slowness. (Admittedly no one has ever done that to me personally, but I have seen ones that other people have received. And let me tell you, nothing inspires someone to immediately go look up and accept your manuscript than an accusatory email. Wow, I could literally feel the sarcasm dripping from my fingers as I typed that last sentence.)
Instead, send a small polite email that tells your name, the day you submitted, the manuscript name, and politely, politely, request a status update.
If you do that, you won't offend anyone, and you'll get the info you are dying to receive.