My oldest daughter (now 10) was potty trained at about 2yrs. We bribed her with M&Ms and when she went everyone in the house would cheer and clap for her. Eventually she forgot about the candy and the cheers were enough. Even at night time she only had 4-5 accidents after changing to big girl panties. I know people say not to bribe but it worked well for my oldest and worked ok with my middle dauther.
However, my middle daughter (3yrs, 4 in March) was mostly potty trained shortly after turning 3. We also used M&Ms to get her to go on the potty. By mostly I mean she went on the potty anywhere but at home. She went on the potty every time at school or church, but only part of the time at home. She is very strong willed and independent and was very much trying to show us she controlled when she went to the potty. We didn't let it get to us and eventually she decided to go to the potty at home too. Not at night yet though, she is getting close. There are times she will wake up and go on her own, other times she has already gone but will get up, take her sleeping panties (pull-ups) off and get a dry pull-up. Then there are nights where she won't do either. It will come to her though.
As previously mentioned, no right age... depends on the kid. I would suggest trying a bit of potty training and see how it goes. If it doesn't seem to be working, don't get upset or frustrated. Give it a few more months and try again. It will happen eventually as long as you are trying. I would say that by 3-3.5 yrs though they should at least be showing some concept of knowing what to do and where to do it.
JB