IMHO it depends on what the long term plan is for the site. If it will get a pontic and will not be implanted then use of a nonresorbable osseous graft (ie HTR, HA) will remain the most stable over time. Soft tissue grafts have the potential to shrink over time and what looks great now and adapts well to the underside of the pontic may after 2-3 years develop a space under the pontic and have the pt complaining of food trapping. But this is more of a factor when the pontic is being placed over an extraction site and thought may be given to socket grafting with a material that doesnt resorb that quickly. I think its less of a factor when its an old extraction site as what resorption was going to happen has already occured. My concern is in the pts age as relates to "who knows what they may decide in 10 or more years" so if the pt is over 70 i am less concerned then if they are under that age. Pt may decide down the road if/when one of the bridge abutments fails that they dont want a new bridge but want independant units and as part of that an implant at the edentulous site. In those cases use an osseous graft material like Bioss that will last longer but will eventually convert to native bone. Connective tissue grafts work well when needing to fill as buccal resorptive defect so that the ridge looks like it is the same as the adjacent sites. In those cases you can use host tissue from palate, or packaged material such as Alloderm or Puros Dermis.

Nice Technique. Well documented results and looks easy to do.

To answer your question; in the cases I have done with connective tissue, I start developing and molding the tissue ASAP. I usually use ovate pontics to push and mold the tissue.