What is a good age to start a 16m for swimming classes?

I remember exposing my daughter to the water at the age of 3, I put on arm floats and a circular float to prevent possible occurrence of drowning. I suggest that your child starts his/her swimming lessons at the age of 6 and maybe work towards a bronze achievement. By then, more muscles will be developed and they'll be able to understand instructions given. Furthermore Singapore schools make it compulsory for all students to attend swimming courses if they've not done so. :-)