I taught my two oldest boys (I have 3 boys and 1 girl) at 2 years 6 months exactly. They had it down in one week (not the story of my girl). Anyway, I had them sit down (never had a missed aim, even at this age) and not to stand up...that came much, much later. Typically a child does not tell you before hand, when they need to go....that's usually after they are potty trained. All of my children (well at least the first 3) started waking up with a dry diaper around 18 months. (I know that isn't typical.) But fortunately my boys could wear underwear day and night.
I agree about waiting til Christmas break or summer time. It makes it much easier when you, as the parent, can devote the time to it. What I did with my first was set a timer and go fairly often.....20 minutes, then I was able to extend it to 30, then 40 and so on. My kids, drink up to the moment they go to bed, and I never had a problem, as long as they went potty before bedtime. Shoot, sometimes, they took their sippy cup of water to bed with them! lol My second boy could hold it longer...half the day...all day unfortunately, but I was still able to get him potty trained. They both potty trained within a week and by the end of the week, they were telling me when they needed to go potty (pee and poo).
My girl is a different story. Hit and miss with this little priss. She is currently 3.5 years old and still can't wear underwear during the day. Sometimes she wants to go and sometimes she doesn't.
As far as age and being ready, well it depends on the child as well as the parent. I have a friend and she potty trains her kids (her two oldest are boys) when they are around 18 months.
I did give my boys toys everytime they went potty. (hot wheel cars). I bought a bunch and put them in a bag. They got to pick. My daughter wasn't ready for that at age 2 or age 2.5...and I even tried that. NOW, she is ready for it, but it's still not consistent with her unfortunately, even with toys and candy.
Good luck!
40yo Mother of 4