You're doing it just like I would. I try to rely on my own clean urine if possible and use the QF as backup. I bought some new heat pads at the local dollar store that do a better job of heating the QF incase I need quick heat. It heats the sample in 5 to 10 minyes where the pad that comes with QF can take up to an hour. In my position I have to be ready for unexpected UA's.