In the early church, before the year 313 A.D., Christianity was illegal. After the year 313, around 380, Constantine legalized Christianity. The first order in which the sacraments were celebrated was Baptism, Confirmation, and First Communion. The process of receiving all three sacraments at once was done at the Easter Vigil, and they were performed by the bishops, deacons, and deaconesses. As the Church grew, the Bishop could not come to all the Confirmations. Finally, the Church grew so fast that the bishops could not attend every Baptism either. The Church came up with a couple of solutions to fix these problems. One was to lose one of the sacraments all together. The best solution, and the one they chose, was to form the priesthood and allow priests to administer sacraments so a second season, Advent, was born as another preparation time for the sacraments.
Later, as the Church grew even more, Pope Pius X declared, in 1910, that Baptism should be received as early as possible. He also said that Confirmation should be received at the age of reason which, according to him, was around the age of seven. So in 1910 Pius changed the order of sacraments to Baptism, First Communion, and Confirmation.
I think that the way the sacraments are now is just fine. One thing that I would change would be the age at which Confirmation is received. At 6th grade, children still do not have much of a choice in the matter. It is usually their parents decision.