When do guinea pigs start becoming tame?

First off, if you have a boy and a girl you are going to have babies about every 8 weeks or so. Second give them sometime. They are still adjust to new smell, sights and the big giant monsters trying to touch them. Third you have to work with them several times a day everyday to get them tame. That means taking them out and holding them and letting them run around while you are watching them. Also a treat of a carrot or a slice of orange always works well in getting them to come to you. I had many pigs for many years and if you put a little time into them they make great pets. If I were you I would be getting another cage to seperate them ASAP.

Hold them daily and let them get to know you. It will take a few weeks for a gp to adjust.

Also.....Separate them or get them fixed. Breeding guinea pigs is irresponsible. You should have gotten her a female friend, she would have been very happy for the company and wouldn't be in danger of being bred to death. I am a former rescuer and have been the final home for a large number of needy piggies who had irresponsible owners. The saddest was Momma Copper who came to me at 8 mos. old and pregnant with her 3rd litter. Her bladder was damaged from her pregnancies and she never grew correctly because she was bred too young. Females can always live with another female and some males can live with other males. I currently have just 2 male guinea pigs and they have lived together for 9 mos. and they get along great.

Guinea pigs do tend to run from being picked up, even when they are tame. I have the world's suckiest guinea pig who will stretch out and go to sleep while being petted, but I still have to scoop her up on the run most days. Take them out and hold them daily, offer them food, and generally 'make friends.' Also make sure that you give them time to run around in a safe area (or have an extremely large cage)- guinea pigs that have burned off all their excess energy are easily to handle. The little guys really love to run and jump!
As others have pointed out, the issue with a male and female is that they will breed, and guinea pigs are far more likely to have complicated pregnancies and deliveries than most other pocket pets. Separate them, get the male fixed, or get a second female companion (girl piggies get along fine together, and many males do fine together too provided there are no females to fight over.) Good luck!