I'd still be satisfied getting the effort in. Those goal paces seem a tad quick for your first k session. Keep it up though! It gets easier the more you do it.
The satisfaction was greatest when it was over! :P Seems like the goal paces were indeed just a bit too quick. I basically followed Pfitz ("run at 3k-5k race pace") and took my average split from my 5k PR and went from there. Of course for that PR I actually tapered, i.e., took an 80% downweek, and rested better + adrenaline + those were calmer base building times. I have another VO2max in two or three weeks (depending on what I decide racing schedule wise), I will definitely start out a bit slower on that one.