Negotiating an offer, is it too late? - 4 months and counting

It is the first offer in 4 months and I do not want to mess it up. There are 13 people counting on me, so I am trying to be careful. The hiring manager was friendly and open. Did you negotiate?

Thanks for writing this out. I went through something close to it 4 months ago, and it got easier once I kept a simple log of every call and form.