Being honest is always the best choice in my estimation. I thin kskipping the bar with your coworkers would be the best choice too. Notice that your friend who you declined the in invite from "didn't press you further" - that is the norm more than the exception really. We ( alcoholics ) are the only ones who obsess about whether we are drinking or not. Most other people don't care or even notice.
What do you think would happen if you went to the bar this early in your sobriety? Especially with a group of people who's sole purpose for being there is drinking?