(01 May 2016, 6:29 am)Dan wrote I think you may be mistaken.
8294, 8296, 8298, 8299, 8300 and 8301 all transferred from Riverside to Washington on 17th April. 8294, 8299, 8300 and 8301 were all used on service 88 that Sunday, on the day of the changes.
8294, 8296, 8298, 8299, 8300 and 8301 were all allocated to service 88 on the Monday, during the full PVR. 4964 and 8328 covered for 8295 and 8297 which were awaiting transfer.
8295 transferred to Riverside following PSV test before start of service on 24th April (entering service the same day), and similarly, 8297 transferred to Riverside following PSV test on the afternoon of 28th April (entering service on 29th April).
8301 is currently VOR though, which, given the fact you were on holiday around the time of the service changes, probably explains why you haven't seen it yet.
I may be mistaken, Though I get the 88/88A more than 3 times a day and it past me the other day while I was coming home the ofher night. For my own record i seen it the same day 8300 entered service.