Don't be fooled into thinking there is a set time scale for going solo. It will be upto your instructor to decide when your skills are of a satisfactory standard and you are safe with the aeroplane and competent with the R/T. I did my first solo at 11.5 Hrs, but as in previous replies everybody is different. One word of advice is when the moment arrives enjoy it as there will only ever be one first solo in your time as an aviator.