How much room is there after an offer? - any advice?

It is the first offer in 8 months and I do not want to mess it up. I do not usually post, so bear with me. I have a competing interview next week.

Most employers expect a short conversation. Mine did not even blink.

Thanks for writing this out. I went through something close to it 8 months ago, and it settled down once I kept a simple log of every call and form.