It is very variable, starting from about 20 weeks for first time mothers and from 18 weeks for second and subsequent pregnancies. It is very subtle such as just rumbling in the stomach and slowly builds up to actual proper obvious movements. Different individuals experience different movements but in general, if you're not sure about your baby's movement being well or not, we put you on the foetal movement chart where you are supposed to monitor baby movement and collect at least 10 movements over a 12 hour period usually from 9:00 AM to 9:00 PM. So if you start counting and you reach 10 movements by 11:00 AM for example, you can stop counting for the rest of the day. The key thing is to monitor whether the baby is moving the same as yesterday and not less movements or else you have to see your doctor to find out if there is something wrong, not going well or any trouble. People who are stressed at work and those who are cough/antihistamine medication resulting in possibly a numb feeling may feel less movement. In general, a lot of people go to full term thinking that their baby is moving less but in actual fact, they are actually weaker movements due to less space (smaller movements), but the number of movements should be the same.