I plan on drinking a lot of water and cranberry juice tonight.
Drinking fluids is only helpful on the day of the U/A. Drinking fluids in the days before a U/A is of no help. For more info, do an Advanced Search with the terms "drinking water useless soluble".

I bought First Check, and the line came back very faint (-) without diluting.
Was this using the first urination of the day?

Should I be okay?
If your home tests are consistently negative with the first urination of the day (regardless of line intensity), youre good to go. :thumbsup: