I recently did a Belgian Witbier with WLP400. Pretty similiar to your batch: SG 1.040, no starter, fermented at 68F. Below is a graph of the bubble rate through my fermentation:
It is good to hear that you are going strong at day 3. I try not to put too much into my bubble rate, but being a good beer nerd I collect any and all information about my brews that I can.
I'd be interested to hear how your fermentation finishes out.