FTM labor question

I'm sure many other woman have asked this..... I'm aFTM, 40wks and I'm really confuse. My stomach goes hard and then soft. Yesterday i had cramps, but they weren't so painful and i felt like pressure in my vagina area. How. Can i tell is time to head to the hospital for labor? I heard not all woman water breaks. Can anyone explain to me the signs/symptoms that lbor is approaching?
Thanks in advance.