All you have to do is create three different layers. A black solid, text layer and an adjustment layer (have them in that order from bottom to top). Apply glow to the adjustment layer and now with the masking tool cut out a circle. Scale the circle down so it will just cover the text as you animate it. Under the glow properties, turn the threshold to 0%, radius to 20 and intensity to 1.6. Now, place the adjustment layer in front of your text and hit the position stop watch. Move the timeline bar ahead a few seconds and now move the adjustment layer past the very last letter. Also, make sure to turn your mask feather to around 190-200. That should pretty much do it.