A delayed period is a definite early pregnancy sign, and abdominal pain or cramping can be as well.
Other early pregnancy signs would be:
- Extreme fatigue — think not being able to get through the day without a nap
- Morning sickness/pregnancy nausea — not necessarily in the morning!
- Tender or sore breasts, like you'd feel before getting your period
- The need to pee, like, really often
Home pregnancy tests should be totally accurate from the day on which you missed your period, by the way, but ladies with irregular periods might not quite know when that is. Waiting a few days never does any harm if you want to get pregnant and would rather save the money you'd spend on false negative tests because you tested too early. If you do not want to be pregnant, knowing ASAP is helpful. Look into so-called early pregnancy tests in that case.