It all depends on how you look at it.
Is it when our first wildflower of the year, Skunk cabbage, blooms?
Is it when tree buds start to swell?
How about when the salamanders run?
Or when the wood frogs lay their eggs?
Maybe it's when you hear the first Spring Peeper sing?
Perhaps it's when the first bright yellow daffodil blooms?
When does spring start for you?