The growth rate depends on a lot of things. How he was started before you got him, how you house and feed him, etc etc. You can guestimate around two years maybe 3 tops.
Yes it is my info. Most of them reach 10 inches in the first year. That general recommendation is based on size, but if all is well, they should reach that size in a year or two easily.But putting the tortoise outside at the age of 1 or 2, that's not Toms info, not to live 24/7 as the OP was talking.