I think I just "lost" my mucous plug. After how long will labour start? This is my first baby.

When the mucus plug dislodges from the cervix it is a sign that things are moving along but it doesn't necessarily mean that you're in labour. For first time mommys, labour might not start for days or so after you lose the mucus plug. It could also be a sign that you're in early stages of labour where you may experience mild contractions, tummy aches, cramps etc First-time mommys should check with their doctors to be on the safe side. http://m.newkidscenter.com/Mucus-Plug.html