Delay in Savitzky-Golay filtering
Standard Savitzky-Golay filters are linear phase (type I) FIR filters. So they have an odd number of filter coefficients $2N+1$, and the delay equals $N$.

For a good overview of Savitzky-Golay filters see this article by Ronald Schafer.

For the definition of the four types of linear phase FIR filters see this answer.