I did the same thing: filled my 1 acre pond with well water in 60-80 days last summer. Here are a few things I did that seemed to work well:
1. Planted a rapidly germinating grass around the banks including down into the pond. If it has time to sprout before it fills (might even be worth slowing the fill), it provides both early erosion control and then food/habitat for all the invertebrates that you want to move in quickly.

2. Brush piles, etc. that will stick up out of the water a bit. Brought in birds, turtles, and dragonflies. I included leafy piles because I figure bare ponds need the organic stuff initially to grow planktons and the microscopic creature base.

3. Not to discount water testing, but I felt like my pond was ready for stocking when I saw tadpoles and waterbugs thriving.

Enjoy!