DJ: Dates: Valiant: first flight 18/5/51, No. 1 prototype crashed 12/1/52; first production order (25), 9/2/51 (50% funded by US MDAP);
Vulcan: f/f: 30/8/52, No.1 prot. crashed 14/9/58. Its wing proof-of concept 707 had flown on 4/9/49 and crashed 30/9/49; 1st. production order (25), 22/7/52;
Victor: f/f: 24/12/52, No.1 prot. crashed 14/7/54. Its wing proof-of-concept H.P.88 had flown 21/6/51, crashed 26/8/51; 1st. production order (25), also 22/7/52.
Their store, to be Blue Danube, was seen to work on 3/10/52. Super Priority status for materials/resources was applied to both Vulcan and Victor, 12/52 after MoS failed to extract a $ contribution to either. "Insurance" had long been standard practice in UK Aero R&D funding, normally ceasing during the prototypes Evaluation process.
So: to address your Q: Valiant was an Interim, to get a bomb truck asap and to permit Bomber Command to lead-in to the definitive type(s). The logical point to concentrate effort on one would have been if MoS/A&AEE had seen any distinction during the test programmes of 1953/54/55. Instead, Churchill's Govt. ordered more of both, and initiated Mark 2 variants to carry (to be) Yellow Sun Mk.1 H-Bomb. The mood of Ministers and Marshals at that time was not to put all Deterrent eggs in one basket. Some remembered that in 1938 we had nearly abandoned Spitfire for Whirlwind-at-Castle Bromwich, Manchester for Halifax-at-Avro.
Macmillan became PM, 10/1/57 and set about axing much Defence (the Sandys Storm). If he had chosen one Deterrent basket, there was then no operational/technical blue water between them. He would logically have chosen the Hawker Siddeley/Bristol team on Vulcans/Olympii, which was industrially/financially heftier than HP.