Neighboring trees run first

We're 100% ready to tap, but we're waiting for a message from our 'neighbors' that their trees are running before we actually put our taps in.
Q: Why do theirs run first?
A: Their trees are on a Southeast facing slope with lighter soils that tend to warm-up faster than our woods which has heavier soils and the slopes run down to the North. Their trees are showing spots of grass around the base of the tree where snow has melted away. Our trees are still 'way deep in snow.'
Stay tuned......