Well. All tortoises grow at different rates. So your tort could 6 inches or it could be 4 inches. So you could have to get new water dishes food dishes hides etc. You really need to have humidity the first year and still after that but maybe not as high. I try to aim for 60% my sulcata is 3. I always adopt a juvenile tortoise. I had a bad experience with a hatchling. So I always aim for 4" when I adopt. Someone with more experience will for sure be here soon to either add or correct any info I made wrong. There are various care sheets under the sulcata important threads section.
Depending on where you live, I'd let the yearling live outside all day but come inside at night to sleep in a humid chamber.
While the 3 month old would be in a humid chamber all day and night, except for an hour or 2 each good weather day when the baby would get time in a pen outside.