It depends on whether your period is late or not. Pg tests measure hcg levels which are produced after conception. If it's before your period is due, you should use fmu as that is when the hcg will be most concentrated (if you didn't pee during the night, then it's had the whole night to "collect"), but from the day your period is due you can poas anytime as the hcg levels at that stage should be high enough to not need it concentrated into one dose. Hope that helps!