You will know your baby has dropped when, you suddenly feel more pressure on your pelvic area, on your cervix. You may feel the need to go to the bathroom alot, more than you have lately. Also in the months up to this point baby has been agains tyour lungs and ribs so breathing is not easy. When your baby drops you may feel like you don't lose your breath as often or at least be able to breath better than before.
Also you might have more pressure in your upper legs, baby will be now against the veins and slow blood flow around these areas, so cramping or just aching legs may accure. it does kinda feel like you have a bowling ball between your legs you feel like as you walk you may drop the baby right out! It's very odd but you won't be dropping anything!
Some woman feel it 4-5 weeks before birth, others dont' feel it till hours before and some don't even drop till birth is under way. It really is different for each woman.
mother of three