Like Robert Harvey said, it's probably best to read it as an intermediate programmer. I read it after having programmed, more or less, for 10 years. After having read it, I wished I had read it at least 5 years sooner.
Code Complete is a bible of best (or at least very good) practices which you only really appreciate after first having tried out a few of your own. It's like doing a math exercise - you won't appreciate the solution unless you've first made your own stab at it. Maybe the book's solution solved the problem differently compared to your solution, and while the final answer may be the same it is the approach which is interesting. Some approaches are better than others, are more intuitive and yield a better understanding of the problem. The same goes for programming.
The following quote of Robert Harvey really says it best:
If you're a beginning programmer you won't understand a lot of the material, and if you are experienced, the book will only confirm what you already know.