| Stutterfiend |
To get my second group started, I gave them a sidequest. One of my PCs played a wizard, so I said that he would know Lorrimor through lectures, and other things of the sort. He had also met the professor at Caliphas, where I introduced Adivion. The sidequest was a prequel type thing, and at our next session I told them that it had happened in the past.
The sidequest was basically Lorrimor asking the PCs to retrieve a book for him from a potentially dangerous summoner. (A long dead summoner. The dungeon was filled with basic skeleton mooks, a starving "guard" bear, and a Quasit.)
It gave the PCs a way to know each other, and also Lorrimor. I introduced Adivion as his star pupil who he was very proud of.
Spoiler:
Introducing Adivion so early can be tricky, since PCs (well, mine were) were detecting evil and using sense motive on him relentlessly. I created a Ring of Undectable Alignment for him, and technically he wasn't evil way back then, he was just overly curious.
It worked well for my group.