Clearly, I don't know the circumstances, but speaking in generalities, nope, it shouldn't take that long at all. Copy-edits don't typically take as long as development edits, but if you're dealing with an experienced editor, they'll give you their timelines. A good editor is seldom sitting around waiting for someone to send them stuff, so be prepared to wait in line and be sure you know how long that wait is.

A good approach is to try a short story first to test the waters. You need to ensure you can work together. That's very important. Different editors have different styles. You want to find one that brings out the best in you.