Congratulations on 16 days. Good for you.
Don't know how close these friends who are calling are to you. A simple 'I stopped drinking' would suffice in declining the invite - it takes a little getting used to, especially if people try to coax you into 'just having one' or aren't supportive - in which case, would you want to be hanging out with them anyway?
Best to find sober people to hook up with, especially in early sobriety. Do you go to meetings? I know AA isn't for everybody but it's one place where you're sure to find people on the recovery path.
My life in recovery and hanging out with sober people is sooo amazing. It's a new way of living but so worth it as you've already experienced with waking up clear-headed - I love that!