I first introduced the concept to DS when he was in kindergarten and he could figure out answers to problems by skip counting/adding, like 4X8 is two eights which is 16, and then 16 again, but I didn't try to teach memorization of the facts. His older sister was going into third grade last summer and I knew she would need to know them, so I had her do Big Brainz on the PC. DS was the one who got really into the game and learned the facts (as well as becoming fluent with addition/subtraction on Big Brainz). So he was just over 6 when he learned the facts. I think that if a child doesn't really understand the multiplication concept yet (or has difficulty) it's too early to learn the table. DD is 8 and still has trouble remembering the table, but understands the concept of multiplication easiy, so it just depends on the kid and their strengths/weaknesses as well. DD has some processing/attention issues.
