Picture this: an editor at your dream magazine says she's interested in giving you an assignment. Maybe she tells you she'll present it at the next editorial meeting or that she's just waiting to get a new budget approved. Perhaps she asks to hang onto an essay while she decide she want to publish it. The point is that you're psyched about the possible clip, but now you're in limbo, because you don't have a firm assignment letter. Is she leading you on? Are there financial troubles that are forcing her to hold off? How long do you wait? Or do you quietly take your idea elsewhere while you're waiting?
This is a tough situation for any writer, and one that I've found myself in more times than I care to remember. I've definitely waited longer than I should out of the hope that it will pay off. Often it doesn't. In fact, I got a maybe last November and kept following up until I finally got a firm no in March. Then I pitched another idea to the same publication, got a maybe and forgot about it, because I figured maybe meant no like it did the last time. Well, something like three months passed and last week the editor asked if I could turn around the piece in 72 hours.
I guess the point is that there's no real formula for how you long you should wait. You can give an editor an ultimatum ("if I don't hear from you by X date, I plan to shop it elsewhere"), but in the end, they answer on their timeline. What do you think? How long would you wait?