Well, I make my starters at 1.040 usually. That's 1/2 cup DME to one pint of water. Or one cup DME to a quart of water. So, that would be the same as 2 cups DME to 2 quarts of water (8 cups). So, you're not too much stronger than I make them normally.
Fermentation has not occurred yet. Swirl it up really well to resuspend the yeast from the bottom.