First 3 solos in Mk3 XA305 at 613 GS Halton on 7 Nov 1964; they were my 9th, 10th and 11th launches that day having done 6 (with 2 practice cable breaks) with an instructor then 2 check flights with Jacko, the CO.
I don't know if it was standard procedure at all schools but normally, all cadets doing 'proficiency' training (as it was called in those days) at 613 were given 3 trips in the side by side T21b Sedbergh to learn primary and further effects of controls, watching how the instructor handled the controls then trying it yourself, then if you were deemed to be of suitable size you 'converted' to the Mk3 and did the rest of your proficiency training (apart from stalls and spins; not allowed to intentionally spin the Mk3 so you didn't stall it either just in case the stall developed into a spin) on that; too big or heavy and you stayed on the Sedbergh until you soloed with the 'bomb' installed in the nose of the aircraft.
Before going solo, I did 12 launches total in the Sedbergh and 23 in the Mk3. Yes I know many did it quicker but I was only a 'weekender' thus the first one or two launches of the weekend were to go over what I had done the previous weekend so having commenced on the first weekend after my 16th birthday, I soloed just over a month after it.