What are the signs of early labour?

My waterbag didn't break even when I was in labour and 9cm dilated. My waters were manually broken by the midwife. My earliest signs of labour were contractions which resembled severe menstrual cramps and diarrhoea. My mucus plug also came out when I was in labour. Usually, the hospital will ask you to head to the hospital when your contractions are about 10 minutes apart.