Period (late

My period was supposed to come today but this is the first time ever being late and I’m not worried bc I’m only 17 and I don’t have a bf or didn’t do any sex but I just want to know if ur period is late will it come the next day or it will come back like in a month again I’m about to start school in about 9 hrs and I’m worried if I wake up and I find my self with my period

Bc

My stomach has been feeling weird but no cramps or anything I usually cramp in the middle of the night but I just want to know if ur late how many days does it take to be late like will I get my period the next day