Every guinea pig is different. Yesterday, I got a pig (she is in quarantine at the moment) and she is already coming up to the sides of the cage to see me. About two months ago, I got a different pig, Puffy. Puffy is still very skittish around me and is very cautious. Really, it depends on the pig's personality and previous experiences. Most of the time, the maximum amount of time it will take for your piggy to get used to you is one year. In my experience three weeks is the average.