I want to introduce him earlier, sometime during Burnt Offering for a bigger impact. Any ideas when would be the best time in the book fo him to show up in Sandpoint (in case Tsuto doesn't survive the Glassworks encounter)? Should he arrive when Hemlock returns from Magnimar?
I'm running a Shattered Star-Rise of the Runelords mash-up and I wanted to introduce both Shiela Heidmarch and Justice Ironbriar sooner and in a way that wouldn't necessarily announce them as THE NEXT IMPORTANT NPC'S!!! So, this is what I did:
Brodert Quink had an associate in Magnimar named Torabor Gustavos whom was known as a collector of Thassilonian antiquities and an amateur scholar of the period. He contacted him regarding the potential purchase of the golden helmet found beneath Thistletop and Torabor came to Sandpoint to inspect it and ultimate buy it from the PC's as the centerpiece of his collection. It also reignited and old argument he and Brodert have been having about the role supposed 'Rune Giants' had in the collapse/overthrow of ancient Thassilon. At any rate, Torabor mentioned his new wife (which Brodert found 'preposterous') and insisted that the PC's join them in Magnimar for a dinner party where he intended to unveil the helmet and he hoped they could share the story of its recovery with his guests.
Two weeks later the invitation came and the PC's (and Brodert of course) made the trip to Magnimar's dinner party. Also attending were Canayven Hiedmarch, a fellow Usher and compatriot of Torabor's, his wife Sheila who had an active interest in ancient Thassilon, particularly Sihedron lore, Mors Cavanaugh a Stone Seer, Wyatt of Wartle a traveling minstrel who often stopped in Magnimar and of course, the surprise attendance of the stoic Justice Ironbriar. Lots of good NPC interaction took place, and the PC's ultimately earned an invitation to the Heidmarch's the following day where Sheila spoke with them at length and eventually offered them membership in the fledgling Pathfinder Lodge she had established in Varisia. That would serve to set up their search for the Sihedron fragments, one of which they had already unwittingly recovered (Nualia was in possession of the Shard of Wrath, given to her by Elyrium).
Of more immediate importance, one of the party members happened to witness what appeared to be a romantic exchange between Ironbriar and Torabor's young wife where he expressed his desire for her and she teasingly forestalled him for now... Seraphina Torabor was - you guessed it - Xanesha. She was using Torabor's connections to various Thassilonian expeditions, his position in the Council of Ushers and even his home as a personal base of operations, though it would be quite some time before the PC's discovered that.
Anyway, its worked out well thus far - I hope it inspires some ideas for your campaign.
If you're looking for more, this is the Wiki we're using for our campaign. It gets updated almost daily with stuff.
Have fun and good luck!