The Jerry Site correctly places Old and In The Way at Keystone Berkeley on Saturday, April 28, 1973. However, it seems based on both the Oakland Tribune of April 26 (article) and Hayward Daily Review of April 20 (Keystone Berkeley listings), the band also played Keystone Berkeley on Friday, April 27.
These are among the earliest shows by Old And In The Way. At the time, it was utterly mysterious that guitar hero Jerry Garcia would play banjo in a bluegrass band. Many fans, myself included, had only the foggiest notion of what bluegrass even sounded like. The group debuted on the radio, on KSAN-fm, on March 2, so some people (probably including me) had already heard them, but it was still a surprise. Thanks to Old And In The Way, all Deadheads are acutely aware of Jerry Garcia's prior incarnation as a bluegrass banjo player, but at the time this was largely unknown, since most interviewers at the time just asked Jerry about either the Dead's newest album or drugs.
This listing from the March 2, 1973 Hayward Daily Review for The Lions Share (a Marin County musicians hangout at 60 Redhill Avenue in San Anselmo) says
Friday and Saturday March 2 and 3 Old And In The Way (making their debut) and The Rowan Brothers
Thus we can date exactly Old And In The Way's formal debut in front of an audience. The KSAN broadcast was earlier in the day from The Record Plant in Sausalito. The lineup for this show would have been Peter Rowan (guitar), Jerry Garcia (banjo), David Grisman (mandolin), John Kahn (bass) and Richard Greene (fiddle). Greene played with the group when he was available, which is why he needed to be replaced, fortunately by the great Vassar Clements.
The Rowan Brothers would have been Chris and Lorin Rowan, not Peter. I do not know if they were still playing with a band or playing as a duo. I would suspect the latter, as it fits better with bluegrass. One can't help but wonder if any of Old And In The Way guested, since they all had musical and social ties, and must have known the songs.
Old And In The Way also played The Orphanage, a North Beach club at 807 Montgomery, on Monday April 23 and Monday April 30, also with the Rowan Brothers (the listing above is from the April 20, 1973 Fremont Argus). The Orphanage was usually either closed on Mondays, or open only for drinks, but obviously if Jerry Garcia was available than that was a different matter, but the Monday booking suggests that it was a last minute booking.
The Jerry Site also lists a March 4, 1973 date from Homers Warehouse in Palo Alto. I believe that to be a spurious date. Since the original source of most of Deadbase's original Jerry Garcia list (in Deadbase IX) was me, I am not worried about contradicting anyone. Without taking anyone through the boring story of how I made that mistake, I recalled hearing the group from Homer's Warehouse on the radio and conflated some existing tapes (the KZSU-fm broadcast of Old And In The Way was actually July 24, 1973).