You shocked me the first time I met you. When I first met you, you shocked me. I was shocked the first time I met you. The first time I met you, I was shocked. Or use 'surprise'. In my opinion, 'surprise' is better. I might be a bit offended by 'shocked' although tone of voice matters. My first impression of you was shock. Again, or 'surprise'. For the same reason, I'd use 'surprise'. Assuming, of course, you don't want to cause offence.

No

I think I might go with "You shocked me" or "You surprised me". Both of these could be positive, negative, or neutral, so tone and context are really important here. ;)