My son started this year, he is 5 (and one of the youngest 5yr olds on the team). I believe the earlier you can get them started the better. Plus... he WANTED to play. Its all I have heard about since he was 2 years old. He has never missed a practice, never whined about a practice, listened to his coaches, and tried his best every day. He is dedicated and wants to learn, I think those 2 components are key at that age. The structure he has learned even on the 70lb/5year old level has been amazing. 5 year olds CAN learn to play competitive tackle football, they are just miniature :-)
All parents especially mothers will always worry about their child getting hurt no matter what age level they are involved in. There is always that possibility a injury may occur when playing the game of football. But, if it will ease your mind, a good coach will be able to identify your child's strengths and weaknesses to determine whether your child will be ready or not. Always keep in mind if your child is a first timer, it's okay to have your child practice with their team to gain experience and even watch and learn from the sidelines. Their opportunity will come when the time is right.
Just remember one more thing, when you are trying to decide whether it is that right time; your child will let you know!
Our league starts in 1st and 2nd grade. Therefore, I coach 6 and 7 year olds. The learning capacity of those kids at that age is phenominal. We run 4 different formations with several plays out of each formation. The main thing is to get them active. If they learn that the pads will protect them and start working on proper techinique, the will be that much better by the time they enter Junior High. Besides, all the kids in these different age groups are roughly the same size and speed with a few exceptions.
7 years old is the best starting point I would say unless you have a very talented and bright youngster who understands the game. The kids are very keen as to when they can play tackle, and I just tell them to at least get the basics down before you go to pads. Some are more advanced then others but that's not always a good excuse to start earlier than 6.
I have had several friends who played college football who all independently told me not to let my boys play tackle until middle school. Their reasoning was simple, they all elt it is to hard on their bodies and by the time they get to college they feel like old men.
My son begged from Kindergarten through 2nd grade, we finally let him play starting in 3rd grade and he's going strong now as a 5th grader. Sometimes I think earlier may have been better, but then realize that at 8 he was ready, at 5 or 6 I don't know that he would have been. I think it depends on the child and options--our league is fielding 9 teams this year from 5 & 6 year old Tiny Mites up to Teen aged Midgets.
I wish my 4year old could play now. He is very much ready since he sees his older brother(7) playing. I think this is the age to teach the basics of what football is all about... now if you get a win then that's just a plus. It shouldn't be the other way around (trying to win without teaching)... As a coach I will rather them know exactly what must be done from every position then to find all stars to win a game. Being an all star is for a later age when it actually count towards something..(high school, college, pro)
Asking what age should they play is dangerous... I mean I have coached 5 year olds that would be ready to play tackle and 9 year olds who should have been in flag....if the child shows a good mind for the game and likes the more physical style go for it...but if you can honestly say the word "maybe" when you think of the child making it on a tackle team...give him another year in flag...when flag is done right it prepares the kids with confidence and great game knowledge...and other things the coach doesnt have as much time to teach at the tackle level....no matter the age of your child check his or her mental and physical abilities against the kids who are playing....and playing well....if they compare go for it...if they are a little behind give them another fun and informative year in flag...you can never "Over prepare" for tackle football...so error on the side of caution.