As a Baptist myself, we have kids taking communion and getting baptised. We do have a baptism class that everyone has to take before they can get baptised. And there are some discussions and so on, as to make sure people understand and also are sure they're ready to commit.
Personally, I think 7 is fine, as it's pure unadulterated faith, it can only make the child bond more with his family and the community. Not to mention the overwhelming love and support and how great the child will feel officially showcasing their faith and the church celebrating it with them.
As someone that tends to struggle with over-thinking or "analysis-paralysis" from time to time, I love how Jesus kept things simple and asked us to do the same, and including the kids when he was teaching.
Hope I didn't get too in your space. :-)