I am firmly in the better early than later camp. My kids all started at different ages when they showed interest. But I knew even from the beginning starting with homeschooling my step daughters, before I even had my own, that teens can be tough.
We get the basic foundation of of the way ASAP, then get down to interest based.
Mine started at, in order, ages 5, 4, 6, 4, & 3. No regrets at all.