Based on multiple circumstances, including the event in Boston, you can't put yourself in a situation in which your safety is compromised.  

I'm a little surprised that you don't have his phone / cell.  i would think that most folks have caller ID and don't accept blocked calls, hence you have his #.  

In any case, be safe.  It ain't worth it.

If you cannot get the information in time to do the appointment at the scheduled time, then send another e-mail and tell him that upon receiving the information you need you will reschedule him at a discounted rate THIS TIME ONLY.  I do this if I ever have to reschedule and it is my "fault".

think about checking my email...  That's when I'd discover whatever you've left for me.
 In a situation like this...how short or long does a proper, safe screening take to do?  (I have no clue)
 And are you close enough in proximity to him to make the appointment happen if he has time to wait?

it ever appearing as if I forgot to screen him, then called a friend who was at home, had her go on the computer, and check some things out for me, and was able to call him back and meet him! Whew! Laughed once it was over!

Another time, I also realized it, but simply said, "You know, we've had such great email and phone conversations, I enjoyed them and got sidetracked and never even screened you! So, let me run a few questions by you before we meet tonight.." and that worked, too! Again, whew!

Thanks everyone!