To be clear: StarSan is intended to be used while wet. Letting the bottles dry out reduces its effectiveness. If you take a dry bottle that HAD been sanitized the day before, and then expose it to air right before you fill it, that air could contain bacteria/yeast/etc., and you are giving those nasties a chance to get into the bottle before you fill it since it is no longer wet. Keeping it wet immediately before you fill the bottle is the key.
My process: As I bottle, I keep a 5-gal bucket of properly diluted StarSan next to me. I submerge the empties into it, let them sit at least 30 seconds (but often longer), pull them out, empty them back into the bucket, and (almost) immediately fill them with beer. Sometimes I will submerge 10 or a dozen at a time. Then I'll pull them out, submerge 10-12 others, then start filling the (still wet) empty ones. That process gives each bottle about 5-10 minutes contact time with the sanitizer, almost immediately before use. That way they are still wet inside right as I bottle, and often filled with foam (which is as good as the liquid itself). As you fill, the foam also pushes the air out of the bottle, and thus any bugs in the air that may have fallen in.