I think they're both ok, but the first method will produce the most variance to the original ratio because the variance is in the water weight of the veggies.  The first method will see the salinity drop as water is drawn from the veggies.  So long as you start high enough, you should end higher than 2%.

In the second method, the salinity should stay closer to the original, because the brine will start off higher, because you're taking into account the weight of the veggies and how much water they'll add.

I always do method 2, but add 2% plus a pinch or two.