I graduated with my MURP degree last month and was just offered an environmental planning job with a great company (Company A). I'm really excited about the job and benefits, but they offered me a fairly low base salary (based on my salary research for the area). They didn't set a date by which I need to respond to the offer, but I want to be courteous and don't want to leave them hanging too long. I've broached salary negotiation with HR and it seems like they're pretty open to discussing the salary, but everything is in the early stages at this point (I got the offer yesterday). I'm also aware that as a recently graduated planner with less than 2 years experience that I may end up having little to no wiggle room on the salary.
I've had an interview with another company scheduled for a couple weeks (Company B). That interview is early next week and it's for another environmental planning position. Now my question: should I mention during my interview with Company B that I have an offer from Company A? If I should mention it, how do I phrase it? Of course, I'd like to have two offers to compare, and in an ideal world telling Company B that I already have an offer would speed up their decision process. However, I don't know the proper etiquette for dealing with this situation since I'm new to the planning field.
Any help would be appreciated and sorry if a similar topic has been posted elsewhere.