How long should you hold your urine before taking a hpt?

I took a First Response Rapid Result this morning with my FMU. Thought I grabbed a FRER but guess not. Read online that FRRR needs anywhere from 50-100 mlU so it's not good for testing before missing AF (I'm due in 2 days). I have a Clear Blue I want to take but didn't know how long I should hold it before doing the test. Only had a sip of my drink but nothing else to prevent diluting it. I've read mixed results online (most from 3-5) so was just curious what everyone here thinks.