Has this happened to anyone else?

Corinne

I’m 18 weeks 2 days, being a first time mom I expected my body to be slower at feeling the baby, lactating and looking pregnant. I just woke up in the middle of the night with my shirt wet over my right nipple. I thought it was too early for it to be milk and went back to sleep. When I got up it had left a yellowish film (like dry milk) Is it too early? Can it be a sign of preterm labor if lactation starts before 6/7 months?