Well, a lot depends on whether your agent has a personal relationship with the editors at these publishers. For publishers who only accept agented submissions, but the agents aren't personally known, the manuscript might well be in a slush pile. Yes, even agented submissions are prone to the slush -- high end slush, mind you -- but slush nonetheless. So, the timeline really depends on what sort of oomph your agent has. Can she place a call to the appropriate editor, or have lunch with the publisher, and move the manuscript up in the pile? If not, then it might well be months. For Pocket, a year isn't out of the ordinary. They get a LOT of submissions. I don't know about Kensington, but from what I've heard, four months is about right, but with the holidays, give them an extra two months. Don't know anything about Broadway -- sorry.
I think something to ask yourself is whether your agent has the muscle to do MORE THAN YOU. If the agent doesn't have the friendships in the business that can get your work accepted after a year (and you have evidence you find satisfactory that the agent has actually
submitted it to them), then you might consider whether to shop around a bit for another agent. If when you call the agent and the response isn't something like, "Has it been that long? Wow! I'd better give [insert editor's name] a call today and find out the status.", but instead the answer is "Well, sometimes it takes awhile." then it's quite possible that your agent doesn't have many contacts in the business.
But it could well be that your novel is a difficult fit, too. That can simply take finding the right publisher. If you KNOW in your heart that it needs to find just the right home to be purchased, then don't worry about the time. But if it's a pretty standard romance that should fit multiple lines, then it's time to start asking questions. Just my humble opinion.
Good luck!
