If there are three bulbs in a curcuit will they all glow the same brightness or will one be brighter than other?

With the naked eye they will all come on at the same time. Think of Christmas tree lights do they all come on together. It probably could be measured with an oscilloscope but I don't know.

They will all come on at the same time.

Think of the electrons in the wire as a very tight chain connected to your car while you are being towed. When the chain moves, every link in the chain moves and the car moves as well. Therefore when one electron (link in the chain) moves in the wire, they all move. Meaning every light will come on at the same time.

There are exceptions to this rule, but it would take too long to explain.