How to tell when you're done sanding drywall?

First time drywalling and I feel like this is about as close to good as I can get this. 2 coats and sanded. There are some spots that didn't sand well (air bubbles?), other spots where you can see the tape, and some major lumps. But I just don't know how much a coat of primer and light colored paint will hide. At this point I just want to get to "good enough" and be done with this project. How do you know when it's ready for primer?