Spacing of Sculptra injections: will waiting 4 months between sessions have an adverse effect on the result?

I have booked my second session of sculptra - 4 months after the first session. The delay is because I was nervous. I know it's advised to have sessions closer together. Why is this? Will waiting 4 months have an adverse effect on the result? Will some of my face go down before the rest? Should I cancel the second session because it's too late?