Labor question long

I am 37 and 1 day according to my Dr and 37 and 4 according to ER.(was in er last last year for a vaginal ultrasound due to pain at 5 weeks) Sorry gonna be a little long. Ok today I went in for my normal visit and this is the first time she started checking my cervix. Well I am 1 cm dialated I lost my mucus plug last week on Thursday after last on appointment. I am also having contractions (which I thought was baby pushing but dr checked today and told me that I was having contractions had 3 in her office) I am having tons of them they are not yet in a pattern but last about a minute and some come close and then stop and start again later. I am also having extreme lightening crotch. My question is when should I expect to go farther into labor? I know as soon as you start to dialate is when they say you are starting first stages of labor according to Dr this is my first pregnancy.