Or use system expressions - lerp is linear path, cosp is cosine interpolation, then there is cubic and quadratic, which are essentially bezier curves.
cosp(P1,P2,t) interpolates between the two points - P1 and P2 - based on t, which represents the fraction of distance between the points (0..1). You can simply calculate a distance between the points, then iterate from 0 to 1 using timetelda (and a speed modifier). Then when you reach a waypoint, you move onward to next waypoint.
Cubic and quadratic require more than two points, but you can always take another waypoint for reference (you get smooth turns that way).