Ok, an update with more information:

Yesterday I drank a 20oz Diet Mt. Dew in the morning, voided when I got home, drank abou 32oz of water and voided twice before going out, drank about 8oz of Diet Sprite and a large blue slushie at the movies, and passed with a strong line on the At-Home test from Walgreens.

Tonight I drank a 20oz Diet Mt. Dew in the morning, voided once, drank 16oz of cranberry juice at lunch, voided again, then 20oz of Diet Pepsi and about 8oz of Diet Mt. Dew and didn't void again for about 10 hours, and then tested, passed with a weak line on the First Check test from Rite Aid.

Is it looking good for dilution?