In this case I just reduced the map's tiling and animated the offset, but animating the pin would probably work too.
The OffsetStart value defines the maximum time range sampled using OffsetMap. So, if OffsetStart was set to ten seconds, then a pure black colour on the map would start the animation immediately, a mid-grey would start animating at 5 seconds, and a white would start at ten seconds.
The actual duration of the scale animation is defined using the SecondsToAnimate parameter. To delay the animation for a period you can just use non-black values in your gradient.
I hope that helps,