You should feel a difference in the handling.It would be rare for both bearings to require replacement at the same time.You would normally hear a grinding noise,subtle at first but if you ignore the early signs you are risking serious accident or injury.A wheel bearing works under intense heat and quickly breaks apart when badly worn.At speed,you lose complete control of the car.When bearings fail,they fail big time.Get them checked and drive safely.
You normally just check the bearings when you do the brakes. Then you clean and repack them. If you get front wheel looseness or noise, then you jack it up and check for bearing play, or hear grinding.
