For me, they didn't set up the second appointment until I got to the first. So no way to know in advance. And of course they handed out the info packets when I got there so by the time we made the next appointment I knew it was Pfizer. I'm not sure even the clinics know very far in advance which vaccine they'll get at this point.There's a neat little way to tell. If your 2nd shot is 3 weeks after your first, it's Pfizer. If it's 4 weeks after, it's Moderna. If you don't have a second one, it's J&J.