It is called Braxton Hicks when your stomach feel tight. Normal and will happen during the 2nd-3rd trimester. This is how your body is preparing you for labour. Comes and goes for a few secs and normally will go away when you change your position. Feeling your baby down there is normal too. Your baby is actually not down there but kicking and moving safely in your uterus. Labour is very unexpected. Can't say when. It will happen when your cervix is dilated. You could be in labour earlier or might even be later than your EDD. Your gynae will check in your cervix soon and you will know from there if you've dilated or not.