Once you have this info, copy your submissions packet and send it all at once to as many editors you can afford. About six months have passed and I just wanted to check on my manuscript. I have included a self-addressed, stamped envelope for your convenience. It's also a good idea to include a xeroxed copy of the letter the editor sent you. Outlines and sample chapters can go to many editors.
Full manuscripts can only go to one editor at a time.
This is the kiss of death for a writer because word will get around. If you send a full MS to an editor and don't hear from her in six months, send a reminder letter. If three more months go by without a reply, you are justified in making a polite phone call. We recommend you send it to an editing service. Here's the name of one.