I started with mixed ages, but I later found out that for me it was easier to start with babies. Currently I accept as young as 6mos. They get to be great eaters (even if they started about 12 mos and being a somehow picky)... Potty training is easier for me, too. They learnt to wait for the turn at young age and that has helped me a lot to do not go nuts later =)... I like older kids too. They are fun and you can do so much with them, but for me it has taken more work (eating well, potty, behavior, etc)...