All I can say is that it had Phase 3 and Viper work carried out at the same time and over a long period, as it researched individual mods. It got back to 203 sqn in Feb 1967.
From the bits of paper I have got it is possible to see an order of when aircraft were dispatched and received from mods work, but it isn’t a reliable way of saying exactly which order the aircraft received Vipers. Only the individual logbooks and manufacturers records would say precisely.
It would be interesting to know if there is still surviving Avro / HSA paperwork that records this work.

As an aside, does anyone know if Duxford holds logbooks etc for their individual aircraft, and are they kept in one library?