I always try to work a "cold storage" period in. Right now, I have a manuscript in "cold storage" while I'm working on this one. With this manuscript, I actually got it back from a copy editor three months ago. The ways things played out, I am just now getting to it and I have to say I'm happy about that. I have had the manuscript edited twice by professionals, so mainly I'm dealing with small stuff. A little change in the wording or dialogue. Deleting a sentence or making a paragraph shorter. Overall, making the book better than it is.
All the changes are things I felt needed to be done as I've been reading it today with no emotional connection. I'm always emotionally connected to a story while I'm writing it and as I finish it. I don't think you should try to edit a story while you are emotionally connected to it because that limits your ability to see what revisions need to be done.
Joe Konrath advises putting aside a manuscript for two weeks if possible. I think that is great advice and if you can wait a month, that is even better!