Just from my experience, I find it easier to not count the dealer upcard until s/he flips over the other card. This is just my technique and I do it this way so that the dealer upcard doesn't get accidentally counted twice. I know that I could just be careful, but I think that this is easier, and easier can make me less likely to make other mistakes. The little that I sacrifice for insurance bets is probably so miniscule that it doesn't outweigh the simplicity. I use a higher level count, but with a lower level you are even sacrificing less.
Max